Doing a Harold Holt 

named after a former Australian Prime Minister who mysteriously disappeared while at a beach to never be seen again. When a person uses it in conversation, he/she is about to go off somewhere without giving any explanation as to why or where.

Davo said he was doing a Harold Holt, then he fucked off without saying where he was goin'

Doing a Harold Holt by Sosen March 20, 2011