Coined by the acting troupe known as "Starkid" (comprised of people such as Darren Criss, Joe Walker, AJ Holmes, and Jamie Lynn Beaty) during their production of a Harry Potter-based Musical: "A Very Potter Musical." Harry (portrayed by Darren) used this term to describe Cho Chang on many ocassions. Can also be shortened to SMFAH as an acronym.
Ginny: Soo, Harry, I guess you really like Cho, huh?
Harry: (with a scoff) Well, DUH! She's, like, supermegafoxyawesomehot!
A girl who is beyond the normal definitions of words like hot, foxy, or sexy. She combines all the qualities of being beautiful with being an awesome person. A combination of terms that alone lack in their individual descriptions.
"Rachel? Hot? Try supermegafoxyawesomehot..."
That one girl at the bar last night was supermegafoxyawesomehot.