Will Smith forgets Men in Black lyrics during impromptu performance

Will Smith forgot the words to his single Men In Black when he made a surprise appearance during Chris Martin's show on Tuesday (21Jun16).

The Coldplay frontman took time out from the band's tour to perform a set at the MediaLink and iHeartRadio bash at the Hotel du Cap Eden Roc as part of the Cannes Lions advertising festival in France.

Will, who had spoken at the event earlier that day, surprised guests at the exclusive bash by jumping onto the stage for an impromptu rendition of his 1997 song Men in Black, from his movie of the same name.

Online footage shows Will beatboxing while Chris plays acoustic guitar and sings the female vocals for the chorus, before Will launches into the rap verse. Halfway through the verse, he realizes he couldn't remember the words but kept the song going by rapping freestyle.

"I don't remember all the words so Imma (I'm going to) keep rapping," Will raps. "I ain't done this song in a long time, Imma just say words that rhyme, hoping it'll be good when I see it and it gets, out on the Internet."

During Chris' set, he performed Coldplay hits plus tributes to late musicians Prince and David Bowie with covers of Raspberry Beret and Life on Mars respectively.

His ex-wife Gwyneth Paltrow was also in the audience to support him and he reportedly joked, "Is there anyone in the room that used to be married to me?” according to New York Post gossip column Page Six.

He is said to have quipped, "At least someone else understands what I put you through," to Gwyneth when he brought Unilever executive Gayle Tifford on stage and asked her to perform with him.

The former couple has remained close friends since their split in 2014.

Coldplay are set to close Britain's Glastonbury Festival on Sunday (26Jun16).