"Dude Rock" applies to most of the mediocre pseudo-rock bands like Nickelback, Hinder, and Theory of a Deadman. Basically these bands are made up of guys that have highlights and wear designer clothes writing songs about how badass they are, how much they love to drink and party, how hot there girlfriend is, and how they can kick your ass. They also right really "sensitive" ballads for the ladys.
The first time I ever heard this term used was in allmusicguides review of Hinder's Extreme Behavior album when the review said that Hinder is "straight up dude rock" or something like that.
Eddy: What do you call all these crappy bands on the radio that sound exactly alike?
Chris: Dude Rock