It always amazes me what kids get up to with a piece of paper. Powered by boredom its almost alchemy what adroit creations rise from the sheet.
When I was a kid we used to create opening and shutting paper thingies. These had different stuff written on the insides of what were a bit like petals. Stuff like You Stink or Go Out with Me or Nice Legs! It was a bit like a folded bird's beak that your fingers opened and closed. If it had a name I can't recall it.
Another thing we did was to tear a piece out of an A4 sheet and create a ragged hole. That became a hole in the back of someone's trousers, which you drew. You then drew a dog with a similar piece in its mouth. To complete the picture you then formed a crease in your index finger and held this crease behind the hole. It looked remarkably like a bare butt!
A similar effect was achieved using a five or ten pound note, when they weren't plastic. A couple of folds were made in the Queen's neck and voila! The royal bottom!
Obviously paper planes were essential origami and they still are. I often find a foolcsap jet whizzing past my face!
A new fad, at least to me, is kids making bang flaps out of paper. Various folds are made to create a sort of 2-ply triangle. When forcibly flicked forward it creates a loud bang and is really quite annoying if you're an adult. Kids love it!
Last but not least there are paper boats. I imagine readers will be masters of the maritime fold.
Did you do anything else with paper?