Free tickets to a U2 gig if you can guess this in one: who is the leader of one of the world's biggest bands, described to the listeners of Radio 1 last week as a "wanker" with an "obviously dysfunctional character"?
Hands up if you said Bono.
The real answer is Chris Martin from Coldplay, and Bono was dishing out the potty-mouthed critique.
The outburst came during an interview with presenter Jo Whiley before a rooftop concert at Broadcasting House on Friday. Bono was keen to reiterate his position at the top of the rock'n'roll hierarchy, while promoting his new album No Line On The Horizon.
But he appeared to forget where he was, using the word "wanker" live on air. Asked what he thought of Martin, he replied: "He's obviously a completely dysfunctional character and a cretin but he happens to be a great melodist and up there with Ray Davies, Noel Gallagher and Paul McCartney." Later, the spiky words were laughed off as all a bit of a joke and blamed on having to get up "early" for the show. It starts at 10 am.
Whiley could have been forgiven for thinking the two men were members of the rock'n'roll hall of mutual admiration. Only a fortnight ago, they seemed happy sharing a stage in Shepherd's Bush to mark the 15th birthday of the charity War Child.
But while U2 have revelled in their status as the world's biggest band, Coldplay's stadium sell-out status has not gone unnoticed. Martin has admitted he compares his own band's work with Bono's mob – "I always view our albums in terms of U2 albums." Maybe the attention has become irritating to Bono, "dysfunctional" even.
Martin has confessed to feeling a lack of love from his fellow rock titans. He said in an interview last year that he dreams about spending quality time with fellow musicians but "they are never interested in hanging out with us". He added: "It's a permanent feeling of being at school and the bigger boys don't want to play with you." How heartbreaking it must have been then to find out that one of the biggest boys in the playground regards him as an onanist. His agent had no comment to make yesterday on how he is coming to terms with this.