Mine is killing lots of Hannah montana hostiles wielding weapons. Gives you a shitload of ammo. Looks cool when you kill them with an RPG. Bodies and weapons strewn across the map. Nice.
I once tried making a hover car from a jalopy, several thrusters, and a few hoverballs. it worked…kinda. Thank god I had godmode on.
So, what do you like doing in single player mode?