The world has changed in 50 years. Of course it has. But in ways that we, sometimes, don’t immediately recognize and never anticipated.

A few months ago, we were driving past the elementary school near the house where I grew up, and I pointed out the spot where we kids were able to scramble onto the roof of the sprawling campus, on weekends, and run around up there for hours.

Which prompted me to consider “all the stuff we did”, back in the late 60s, early 70, “boyish antics” that were mostly ignored by parents and authorities — but could land us in big trouble, in the anxious year 2019.

Like playing “war” with realistic-looking toy guns and contriving “contact explosives” from chemicals found in the chemistry lab at high school.

And, note: I would recommend against trying any of this, in the second decade of the 21st century.

The rundown:

–Toilet-papering someone’s house. We did this maybe three or four times during a couple of teen years. (As soon as we could drive, basically.) In theory, it was about kids who knew each other going out for an 11 p.m. raid and leaving behind lots and lots of unrolled TP — in the trees, around the chimney, on the roof. To be found, by the victims (often, our own pals) in the soggy morning. Just good fun and no real damage done, aside from the hassle of cleaning up.

But imagine how that would be interpreted now.

“Hey, there are three or four teenagers sneaking around at the house across the street. Kids I’ve never seen before. They look up to no good. Better call the police.”

And a few hours before, we would have gone to the local grocery and bought 50 rolls of toilet paper. In theory, the cashier could have called the manager, who might have demanded to know what we planned to do with all that TP. But back then? A conspiratorial wink from the cashier.

Now? I’m thinking we could end up spreadeagled among all that TP, perhaps arrested for vandalism or violating private property.

–Setting off fireworks, which were illegal where we lived.

Then? Well, don’t set anything on fire.

Now? A ticket, at the least. Maybe some time in the station. Might depend on the type of fireworks.

The most significant example of this? On another TP raid. We had just finished a very thorough job, in a quiet suburban neighborhood. My idea was to cap the raid by throwing a thoroughly illegal and fairly loud and powerful firecracker, known as an M-80, on the lawn — to wake up the house, of course — just before we drove away at high speed.

What made this memorable, if not notorious, among our set, was that I had the M-80 in the pocket of my green T-shirt — next to a box of matches. I never lit any matches, but the fuse of the M-80 must have scratched against the striking strip of the matches and somehow ignited, because as I was hustling to the car I saw a flash in my shirt pocket. I made one try at grabbing the burning element and (luckily) missed, and then the M-80 blew up with a deafening roar. (My ears rang for a couple of days.) My accomplices joined me in the car, and someone said, “Why did you throw the M-80 early?” Having not seen the singed, foot-wide hole in my T-shirt, nor the smear of blood on my arm and chest. (I still have a scar.)

Then? I ignored suggestions of going to the hospital, and my parents were pretty much cool when they saw me walk in with a shredded, smoking T-shirt and head for the shower.

Now? Parental condemnation, at the least. “You could get in big trouble doing that! Do you want a police record?” Also, perhaps the attention of authorities, had we been pulled over — a car full of teens and a hard-of-hearing driver with a hole blown in his T-shirt. Something about that must be illegal.

–Playing war. Four, five, six of us divided into two teams, and one side hid and the other group came looking. (Hide and seek with toy guns, basically.) It could be inside someone’s house. (My mother was amazingly cool about that.) Or in a backyard. Victory went to whoever first shouted “I got you!” and demonstrated a line of sight.

All of us had replica weapons of some sort, which were sold in most toy stores, 50 years ago. Some made rat-a-tat sounds. Some did not. I tended to favor my plastic Thompson submachinegun that looked a lot like the weapon my Combat! hero Vic Morrow lugged about in that World War II television series.

(And, note: I have never carried a real gun anywhere, at any time; never owned one.)

So, imagine, looking out the window of suburbia on a summer afternoon, and walking past are five or six kids, 10, 11, 12 years old, all of them with a (fake) gun.

Then? “I know those kids and those are not real guns.”

Now? “Call 911. Immediately.”

–Mixing our faux skirmishes with our cavorting on the roof of the elementary school. A doubleheader of dereliction. It made our little battles almost 3D, once we got up on the roof, maybe 20-feet high.

This was during an era when the playground areas of public schools in my hometown were left open 24/7.  (Classes and offices were locked.) Adults could walk in and play basketball or baseball. Kids could play on the bars. Or you could play the more elaborate version of “war” by going to that spot by the kindergarten room where we could get a foothold and scramble up on the roof — and the whole campus was interconnected, at the roof level.

Then? Nobody ever challenged us. No one ever made a complaint, far as I know — not for a tame session of over-the-line on a Saturday, nor even for walking in with our toy guns and climbing on the roof.

Now? A very strong chance of attracting a police presence, the creation of a dangerous situation and potential censure or punishment of the school district for leaving itself at risk of a personal-injury lawsuit, had one of us fallen off the roof.

–Brewing up “contact” explosives. The guys taking chemistry were behind this one. The word “explosive” makes it sound more serious than it was, but it did in fact make a little “pop” that could startle, when touched or stepped on.

It required only a few ingredients. Iodine was involved, as I recall. The poppers could be mixed at home or even at school, in a spare minute, in the high-school chem lab. The result was a little, granular pile that was inert when damp, but became unstable as it dried. The tiny bits my friends made had about the same power as a gunpowder “cap” in a pop gun.

The dream, I suppose, was for a faculty member to sit on a contact explosive that actually went off. (None did.)

This one seems hard to believe, half a century later. If some kids tried contact explosives now, there would be trouble. Maybe a lot of it. Expulsion, possibly. The authorities might have been called, and they would have wondered how much more serious the building of these “explosives” could get. The word “bomb” might have been uttered. Certainly, everyone involved would have been questioned, perhaps detained.

The point, again, being that in the late 60s kids could do stuff like that. Which, today, boggles the mind.

Toy guns? No longer for sale, and anyone carrying one seems to be considered a potential shooter. Brewing up explosives of any sort? A bomb factory, maybe ATF involvement. Playing war on the roof of an empty school? Breaking and entering, toting banned toy guns, trespassing. Creeping around a house and leaving behind toilet paper? Vandalism, for starters.

And the thing was … we were considered good kids. Rarely in trouble. The stuff we did … most people would have put it under the heading of “good, clean fun”. Back then.

No, really.

Half a century later, we would be crypto-terrorists. With our histories on file with the authorities.

Much has changed, in 50 years, and given how all this would be viewed today, I’m sure we would have been warned off by parents or older siblings.”Fun and games” come in far different packages, now.

The assumption back then was “kids at play”.

Now, that is a dangerous assumption. For everyone involved.