When two males acknowledge having hooked up with the same female but not performing sexual intercourse. They never entered the igloo but merely explored the vast tundra much like a penguin.
Bro #1 "Dude did you bang that chick last night?"

Bro #2 "nah dude... I only got to 3rd base"

Bro #1 "me too! Penguin brothers!"
by Bagel2135 February 7, 2014
Get the penguin brothers mug.