Ghost Cup 

a term used(in beer pong)to label a cup that has water or beer beneath it. When a ghost cup is hit it slides and moves around the table as if a ghost were moving the cup.

"Hey! Clean up those ghost cups!"
"Make sure the table is dry we dont want any ghost cups."

Ghost Cup by mburket March 15, 2008

Ghost Cup 

A beer pong related term where the middle row of the rack has been removed. All that is left is the back 3 and the front cup. The removed/invisible center row creates difficult perception.

I can never hit that dreaded Ghost Cup!!

Ghost Cup by Party Guy March 31, 2009