I live in Alabama, so as you might guess 'Sweet Home Alabama' is an obligotory song in any band's set around here, whether you're a punk, rock, or hip hop outfit. And after that, pretty much anything by Skynyrd people will scream for (and yes, 'Freebird').
Then of course, there's always...
Mustang Sally-which we refuse to do
Brown Eyed Girl
Come On Eileen by Dexy's Midnight Runners
Angel of Death by Slayer
Down in the Park by Gary Numan & Tubeway Army
oh wait, this was supposed to be most crowd-pleasing covers

Just jokes on the last three of course.