A word that apparently is Scottish, but you use it by calling people that are idiots "idiots" without them realizing it because... well, they are idiots. Luckily, great minds think alike, so both me and the Scottish know what is up.
"Dude, Jim is such a fucking numpty, he keeps eating shrimp whole, he doesn't take off the carapace before he shoves it into his fat little mouth."
A person who has gone and made a fool of oneself; with excessive amount of drug use, specifically frying one’s brain and disengaging in all use of basic motor functions.
A numpty
A SCUBA diver, usually of Open Water equivalent, or less, certification. They leave their fuckin' gear strewn from one end of the charter boat to the other, enter the water without their mask, air off, still holding their fins, kick the shit out of the coral and anything else nearby, exhibit no bouyancy control, frantically signal OOA after 5 minutes, and generally gob off like they know everything.
"This is gonna be a tech diving trip. I got no time for fuckin' Numpty Divers..."