Here's a nice, easy little prank to pull in a public place.
Get some super glue and take a quarter (any coin, doesn't matter). Then glue the quarter to a table or sidewalk in a public place.
Note: I am not responsible for any actions you do. Some of these pranks are not very safe. Use at your own risk.
This place has at least 500 pranks. This guy pulled of tons of pranks at college.
AAA Joke Server
Tons of jokes about everything. At least 300
Tons of jokes, viewer submited page too.
50 fun elevator jokes
Want some fun in the elevator?
Canonical List of Pranks
Short List of Pranks