One thing wrong with this movie! *spoilers*

Kirk Lazarus: Everybody knows you never go full retard.
Tugg Speedman: What do you mean?
Kirk Lazarus: Check it out. Dustin Hoffman, 'Rain Man,' look retarded, act retarded, not retarded. Counted toothpicks, cheated cards. Autistic, sho'. Not retarded. You know Tom Hanks, 'Forrest Gump.' Slow, yes. Retarded, maybe. Braces on his legs. But he charmed the pants off Nixon and won a ping-pong competition. That ain't retarded. Peter Sellers, "Being There." Infantile, yes. Retarded, no. You went full retard, man. Never go full retard. You don't buy that? Ask Sean Penn, 2001, "I Am Sam." Remember? Went full retard, went home empty handed...

People with intellectual disabilities go through puberty just like everyone else and have urges and desires too. Fact is, someone with a mental age of 7 or 8 doesn't understand these feelings and so can get very frustrated by them - end up engaging in inappropriate behaviour like masturbating in public etc. It's another sad thing about intellectual disability, most of these people are physically fine and prone to the exact same urges as everyone else but with little understanding of it and less likelihood of engaging in sex.