We were a very geeky bunch of late 70's-early 80's suburban American white boys in my neighborhood where I grew up.
But my all time favorite one that makes me laugh every time I think about it, was how we rigged up parachutes to our bikes using twine and trash bags. We would ride down the street as fast as we could, and then let the parachute out, which was tied to the end of our banana seat. We thought we were cool funny car racers.
Another one was inventing a previously unheard of cuss word that we could use around adults while winking at each other and giggling. Koomaka, I think it was.
So what are some geeky things you did when you were a kid?