when you have sex and your intercourse partner cums on you're vaginal area and you forget to clean up and it dries up and stays on your vagina and it hardens into a crust
tabitha: omg i got so drunk last night i woke up with vagina crustaceans
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.
When a woman goes without showering for a long period of time her vagine flaps develope a sort of crust that oderous. If this happens ladies, SHOWER IMMEDIETLY!
"Daayymm that chick i banged last night had a nasty case of crusty vagina flap!"