As Earl was 16 of the time of this recording (and the youngest of the bunch) Mr. Teen would be Earl.
They both are “Mr. T,” in a sense — Thebe and Tyler.
Also, if you want to dig deep, he might have left unstated Wolf (Mr. Teen Wolf), which has a lot of symbolism for Tyler (with his alter-ego rap persona being Wolf Haley, and WOLF being his upcoming 2012 album).
To help improve the meaning of these lyrics, visit "Orange Juice" by EarlWolf (Ft. Earl Sweatshirt & Tyler The Creator) Lyrics and leave a comment on the lyrics box