A word substituted for any other word, generally an insult.
You stupid... buttchink!
1) An insult used when no other can be thought of or when all others have been used up.
2) One who is extremely clueless or unskilled, especially in the fields of mathematics and computers; the opposite of a geek or nerd
Joe is a buttchink for defining my word before I did.
"I got a t-shirt with pi on the front from ThinkGeek!"
"wat is pi"
"What!? You stupid buttchink!!!"