Olly, 31, was told to pick from judges Rita Ora and Cheryl Fernandez-Versini and his co-host Caroline Flack.
The cheeky singer admitted he would snog Rita, 24, and AVOID 32-year-old Cheryl – but only because she is married.
He told Radio 1: "She's got a partner, and I would like to avoid getting into a fight with her husband."
Perhaps unsurprisingly, Olly confessed he would marry 35-year-old Caroline.
He said: "I feel like we have known each other a long time. We love each other on more of a friendship level.
"Back in the day we were both single, you know, who knows what might have happened. It would be weird if I said I fancied her now because I've got a girlfriend."
Olly has been in a relationship with model Francesca Thomas since 2013, after they met at V Festival in Chelmsford.
During his hilarious game yesterday, Olly was asked the question for a second time – but given the choices of Simon Cowell, Nick Grimshaw and Harry Styles.
"I would marry Simon, because I want his money," Olly joked. "I would avoid Harry, but only because I've heard Nick's a better snogger than Harry!"