When one is stoned but not quite retarded; basically on the border of being alright and just fucked up. Forrest gump was not normal but he wasn't retarded, hence the perfect comparison to being not fully baked.
Pablo: everyone stoned yet?
Daniel: I'm still pretty sober...
Chris: I'm fucked up...
Alex: I'm Forrest gumping over here, 2 more hits and ill be stupid!
the act of being overly nervous or socially awkward around a beautiful girl
"Dude, quit Forrest Gumping and go talk to her already"
"So what did you and that chick do last night after i left?"
"I started Forrest Gumping when she took her shirt off, so she left"