A term coined on the internet, most likely at either
Something Awful, 4chan, or
YTMND.
Generally refers to a girl with ample breasts and/or buttocks, implying that these would be an adequate substitute for
airbags. Most often applies to anime girls, due to the fact that many are drawn with breasts twice the size of one's head. This term can be applied to women irl, though caution should be exercised.
Bob: Forget
D cups, those things are freaking
GG! And an ass to match, damn!
Ted:
Safe driving at its finest, my friend.