Harry Dunne and Lloyd Christmas, 'Dumb and Dumber' (1994)
Harry and Lloyd represent the intellect, maturity levels, and horniness of two 11-year-old boys stuffed into the dorkiest manchild packaging. When they're not on road trips, they're sub-Jerky Boys pranksters taking joy in the others gastrointestinal misfortunes. (OK, that applies to the gents when they're on road trips too.) The brothers from other mothers have somehow weaponized their stupidity — just ask any state trooper or the traveling companion they sing "Mockingbird" to — and there isn't a frozen ski-lift poll they wouldn't lick. Even if they butt heads, another stupid move resolves their differences. When Lloyd swaps their van for a minibike, Harry screams, "Just when I thought you couldn’t possibly be any dumber, you go and do something like this — and totally redeem yourself!" Harry and Lloyd are a ying and yang of brainlessness. Accept no substitutes.
Dumb Factor: 8