Sneak into your boss's office, find his or her stack of business cards, write colorful messages on the back of a handful of them, & shuffle them back into the stack. Examples include:
"I'm not wearing underpants"
"Don't really call me - I'm just handing these out to look busy"
"50% discount to all N.A.M.B.L.A. members"
I hope it goes without saying to disguise your handwriting.