Justin Timberlake was allegedly introduced to the band by new band member Fergie, and got a chance to hear the track that will.i.am created. Impressed with the music, Timberlake helped write and sing the chorus.
Timberlake was in the midst of promotion of his debut album, Justified, and his label Jive Records was concerned about possible overexposure. The Peas were worried about this, as getting some assistance from an established pop star like Timberlake had been the original point of this song. A compromise was reached eventually in which Jive gave clearance for the vocals of Timberlake to be released on the song, but he does not appear in the song's music video nor is he officially credited on the song as an artist.
Yeah he was everywhere at that time. Like I Love You and Cry Me A River were on the radio, he was in every magazine, on MTV and BET, doing Leno, Letterman, etc.
it was their first mainstream single ...probably they were worried he would have gotten all the attention and not them!!!and they were right in my opinion!