Back in black?

When Black Eyed Peas bandleader joined Nicki Minaj during the VMA pre-show Sunday, outraged fans slammed the 35-year-old rapper for appearing in blackface.

" wearing blackface!? What a racist!" fakeart123 tweeted.

Adds TSCMoncton, "Anyone notice that painted himself in blackface? I sure hope there's some kind of meaning behind a stunt like that."

Blackface -- which first gained popularity during the 19th century -- typically promotes racist stereotypes toward African Americans.

In addition to his face paint, wore head-to-toe black (including a shiny hair piece in the shape of a side-mohawk).

" just sent us back 1,000 yrs... Really sir, #Blackface in front the grey ppl!" IAm_Danie wrote of his appearance.

Snipes FrankieVtotheD, "And what the hell is going on with Did he take a dip in the Gulf before the show? I didn't know blackface was back in style."

Tell Us: Do you find's blackface offensive?