Riddle for 12/31-1/6

Last week's answer was:

"Each person paid $9 equaling $27 total and then you MINUS the $2 that the bellhop took and you get the $25 that should have been paid."

This week's riddle is:

"The man who invented it doesn't want it. The man who bought it doesn't need it. The man who needs it doesn't know it. What is it?"

Hmmm......