1 - An adjective used to describe a great feat or phenomenon.
2 - However is not so great when used as a boy's first name. Then and only then is it an insult to that boy.
1 - "Man did you see that reverse belknap he pulled on his board?"
"He totally belknapped that chick, eh?"
"You just got belknapped dude"
2 - "That guy's name is Belknap, that's sad man... his parents must really hate him"
"Boy named Sue? More like, boy named belknap"