A dinosaur that goes to parties, raves, and the like on psychedelic drugs which are but are not limited to:(Lysergic acid diethylamide) LSD, ecstacy, or shrooms.
Dinosaur can refer to tall people, beefcakes and the like.
X: Hey did you guys see Marklar at the rave last night?
Y: Yeah man...he got big.
Z: Dude, he's a psychedelic tyrannosaurus rex, fo sho.
A: Dude check it out. that guy there is trippin' hard.
G: He's totally a psychedelic tyrannosaurus rex.