The fan posted an advert on Gumtree for two tickets to the band's gig tonight (October 9) at the O2 Arena.
NME reports that the advert reads: "The reason these 2 tickets are for sale is because it recently became apparent that my girlfriend (now ex), who was supposed to be coming with her friend, has been fornicated with 2 other men during our 3 year relationship. (sic)
"It is therefore necessary that the people purchasing these tickets be attractive females that will pose in flirty photos with us at the Radiohead gig."
He finished the message by adding: "The highest form of love for Radiohead is also mandatory. Sex after the concert is optional but encouraged."
The notice went viral after being tweeted by Breaking Bad star Aaron Paul, who also was at the concert tonight. He said: "Whoever this guy is please find me at Radiohead!! I MUST hangout with you!"