An act of pulling the back of a person's underpants upward sharply until the waistband is stretched up to or over the person's head, especially as a practical joke.
Origin
1990s.
Definition of atomic wedgie in US English:
atomic wedgie
noun
US slang
An act of pulling the back of a person's underpants upward sharply until the waistband is stretched up to or over the person's head, especially as a practical joke.