When you go to happy hour after work and purposely or accidentally don't invite a coworker, associate, or friend.
Similar to lunch finger.
Sasha: That's so rude! If we leave now, then she won't know which bar we went to.
Joe: Duh! We don't need to invite her for all her brown nosing with the boss all this and last week.
Sasha: Sigh! Hurry up Randolph! Tell Charlene we giving Judy the Happy Hour Finger once again and ditching her here another time.