An adjective used to discribe ones behavior. Depending on the context can be really good or really bad, but always denotes an extreeme.
My idiot friend was being such a third level, telling everyone how i spilt an entire pint of Guinness on myself!
by Go-man May 26, 2006
Third level is also used frequently as a noun, such as in this pensive statement:
"ah, Donny...what a third level!"
by Go-Man November 28, 2006