slap debt

When someone wins a slap bet but has yet to deliver the slap. This may be due to a desire to strategically time the slap or, more commonly, the lack of fortitude to strike a fellow human being.

"Dude, I heard you lost a slap bet to Tracie last week! That must have hurt!"

"Naw, she still owes me a slap debt. She doesn't have it in her."