makeup to cover it, but it never looks right  unless you get a pro Hollywood make up artist

or

a leech which sounds pretty revolting but it's the quickest

RH

Try the pencil eraser trick...

http://www.ehow.com/tips_3556_3.html

Hickeys suck!  I'm still cursing the last person who left a mark on me.

Go to the Macy's cosmetics counter and get the trial size kit of Dermablend.  It will probably be next to "Benefit" cosmetics.  It's $16.  Don't buy the full size kit, you won't need that much. You blend the colors until it's right and it won't even shower off until you use makeup remover.  I've heard from others you can even cover a tattoo with it, and a friend of mine definitely was able to cover his hickey (no, I did not give him the hickey, but he had to hide it from S.O.) with it.

Cancel your date to a later day. She will notice. Good luck!