The female equivalent of a sausage fest. A party or gathering consisting of numerous women with little to no men present.
"I totally went to the bar hoping to meet some guys, but when I got there it was a total clam convention."
A social gathering in which the vast majority of the overall group are women resulting in an abundance of vaginal presence.
Sam: "Bro, we're the only guys at this party."
Brian: "It's definitely a clam convention."
Sam: "What's that?"
Brian: "When the V's severely outnumber the D's. Opposite of a sausage fest In other words, time to go fishing!"