I laugh at:
-guys caught primping and preening in public washroom mirrors...
-motorcyclists who clearly have no idea how to ride
-motorcyclists caught in a huge rainstorm
-gangsta white guys
-rednecks who think Bud is a premium beer
-fans of da Laffs
-huge men on little scooters
-guys with pimped-out 1992 Honda Civics...no, I swear at them
-many, many others.
Some more:
-teenaged girls who think they look hot when they dress slutty
-old people wearing (yellow/pink/green/orange) rubber bracelets because they're trendy
-a guy who won't move out of his parent's basement at age 27, and wonders why he can't get the girls
-doofuses with big scientific "discoveries" who probably don't have a clue about the foundations of logic, nevermind scientific method:
I'm smarter than the scientists!