Urbandictonary says thus
Main•stream (mAn’strEm’), n., adj.
1) A genre in music and other forms of media that is often defined by widely-accepted and currently-popular standards, trends, and hypes that have been established by the media, typically resulting in the promotion of superficial traits.
My popular friends accept me because I'm hot and I like all the mainstream artists on MTV
Mainstream is the larger public, the masses, the big crowd. Things that are or become 'mainstream' are the things that currently sell the most and gain the most popularity.
Hip Hop has become mainstream and is being worn-out by the masses
A gigantic brainwashing cover that the media and the government uses to blindly mislead people into all going the same way. Mainstream should die. I hate people nowadays because they are all the same: Same trend, same bland as pigshit personalities, and same predjudice. Rap is known for influencing mainstream. So is Hip-Hop.
Mainstream should die.
My fave one