TI is fun. I made a quadratic equation solver (easy) and a radical reducer (harder). Someone got my calc and stole my games, and radical reducer, so I made a little bomb program to overwrite his copy next time I sent him something

I have a fake mem clear program (actually accessed when someone tries to reset!!), but never leave it on when teacher is clearing calcs. Except on accident one time, when he just so happened to choose clearing all instead of just RAM because he knew about my quadratic solver and radical reducer. I don't get that, though, because if I made it, I must understand the concept very well, and they have "made by Matt" written all over them... And I later found that it explains how to make the quadratic equation in the math textbook...
What's really fun is the Mario level editor, though.