(adj.) awesome, outstanding, splendid.
Often used to describe exceptional math talent, especially that having been inspired by the great 70's and 80's disco/dance/pop singer Donna Summer. May describe a noun causing lack of care towards math homework, due to Donna's mad beats.
#1: Did you see they figured out how to prove number 17 on our Real Analysis homework?
#2: Yeah, that proof was so Donnarific!
#1: Too bad I still have no idea what's going on in that class.
#2: Who cares about Real Analysis when you've got Donna!?!