A passenger motorcycle seat addendum where extra seat-foam padding is added to the seat to provide a protrusion for the passenger (usually a female), to push against with her groin under hard braking. Usually used in conjunction with having her hands placed on the tank while her boyfriend/husband acts like a hooligan in traffic.
"That vagina knuckle really saved your lower back when that mini-van pulled in front of us and you had to slam on the brakes."
A contraction of the vagina that repeats several times per minute. In humans, the abrupt rush of air into the body of the uteris causes the vaginal flaps to close, creating a "hic" sound.
William: What the Fuck was that noise?
Mara: Sorry, i get the Vagina Hiccups when im cold.
William: Bitch make me a sandwich.
Mara: thats soo cruel!
William: Shut up cunt.
although the word seems to describe a crusty old vagina, it is actually a really cool nickname for someone with the name gina. Although they might not like it, its hilarious.