1 definition by fisdpdt

A mass text message or email that informs your friends of an impromptu social event.
Researcher 1: We've been sequencing DNA for 13 hours; I need a ton of beer and a dance party, in that order.

Researcher 2: Hell yeah! I'll put out the bat signal.
by fisdpdt June 1, 2007
Get the Bat Signal mug.