someone you would totally have sex with.
Wow that guy Matt is totally sponge worthy.
A phrase coined by Elaine on the TV show "Seinfeld." Refers to Elaine's favorite kind of birth control that was ultimately taken off the market. Elaine bought all the remaining stock she could get her hands on and then hoarded her stash of sponges. She defined her dates as being "sponge-worthy" or not i.e. if they had sex. If he was worth using one of her hoarded sponges!
Jerry- I heard you went out with Bob last night. Was he sponge-worthy?
Elaine- VERY sponge-worthy!
Or alternate response from Elaine-I don't waste my sponges on just anybody. He has to be sponge worthy, Jerry!
from "Seinfeld": an attractive man, worthy of being a woman's next sex partner, particularly when her preferred method of birth control is the contraceptive sponge, and her stockpile of sponges is limited (since the only manufacturer had discontinued production).
Elaine: "Well, he's nice enough, but I'm not sure he's sponge-worthy."
In spite of his diminuitive pecker and his disdain for bathing, his sarcastic wit made him just barely spongeworthy