To menstruate. (Derivation: One hits the tiny '57' on the side of a stubborn bottle of Heinz ketchup to encourage it to pour.)
I mysteriously crave french fries when I'm hitting the 57.
by Jonathan Harford December 14, 2003
or "Tapping the 57," which means to masterbate.
"Yeah I couldn't fall asleep last night, so y'know...I tapped the 57."
by Jimmy Paladino July 26, 2005