A creep dash is a move in halo when you manage to assassinate someone with a beam sword while invisible, and you were undetected by your victim. The creep comes from "creeping up" on someone, and the dash comes from what happens when you lunge at someone with the sword in the halo series. This term can be applicable to any fps with a one hit kill melee weapon (tf2 for example)

A casual invitation / threat used by an individual that is not afraid of fucking someone up.