When a group of people laugh at something very funny and find it's not funny anymore, they go back to a normal or straight face, however, if someone has been drinking, high or slap happy, they will continue smiling.
For example, a family are having a dinner together and the waiter or waitress comes to your table and says have a great day or night and you say thank you and of course who ever has been drinking, high or slap happy will continue smiling when the wait they walk away. You say to who ever is still smiling has a hanging smile.
by TroysBallsDick629 October 19, 2014