When two people go in for a handshake and one person puts up knuckles and the other person goes for
a standard handshake. A fucked up handshake or a fucked up attempt at one.
The boss went to shake my hand and I gave him knuckles on accident. What a knucklefuckle.
knucklefuckle: define #2
ramming a whole fist up one’s anus, while jizzing on his/her genitals.
i totaly knucklefuckled that tramp last night in the hotel room.