The act of penetrating both a woman’s anus and vagina with two fingers each, on the same hand. The hand should be held stiff and look like a curved “live long and prosper” hand sign.
“Yo I did the fuckleknuckle on suzy last night”
“Doesn’t your hand hurt bro???”
“Yeah but the carpal tunnel is worth it”
To beat someone in a contest of physical suction force, especially in such a way that leaves them humiliated and ashamed but simultaneously wanting more.