What are some fun pranks to do at night?

Do the shaving cream thing.

Tickle their face, yada yada.

It's classic.

:]Other more advanced fun pranks to do are * egging cars, * dressing up in your other house mates clothes, * drawing things on peoples feet and putting their socks back on while they are pased out, * ringing pizza hut and ordering a pizza for next door i'm sure there are lots lots more. :P