Bashwagon
A particular kind of bandwagon where participants routinely deride or denounce (bash) a particular object/person/concept merely because it is deemed popular to do so.
"Wayne Rooney is a thug!"
"You've never met Wayne Rooney, you don't know anything about him other than what you've read in the media - get off the bashwagon"
"You've never met Wayne Rooney, you don't know anything about him other than what you've read in the media - get off the bashwagon"