In the literal sense, something utterly uncomfortable and unnatural--an aberration. In addition, a complete asshole; someone whose presence makes you wish time travel existed so you might jump back to their conception and prevent it. A total cunt.
"You're such a fucking twat knuckle."

"My twat knuckle is really achy today!"
by Narwhal Rider March 3, 2009
Get the twat knuckle mug.
an insult that you call a female, or a male who has had a sex change, when they finger themselves frequently.
Man, look at Serena over there digging in her pants, damn "twat knuckles "

by Jaime M. Tyler January 15, 2009
Get the twat knuckles mug.