Katy Perry's boyfriend is dating her because she has big breasts.

The 'Waking Up In Vegas' singer is convinced her impressive assets won over Gym Class Heroes frontman Travis McCoy.

The 24-year-old star said: "I'm probably going to get in trouble for saying this, but Travis said he was never a boob guy - he was always a butt guy - until he met me."

Katy admits she only recently realised the effect her womanly figure has on men.

She explained: "I didn't know how to use my curves growing up. I was a little boxier. But now I understand that I'm so attractive because I have that curvy thing.

"I'm not like Jennifer Lopez and Kim Kardashian, but it's there. That hourglass is in there somewhere."

Katy shot to fame when her hit single 'I Kissed a Girl' was released last year, but she insists she never smooches strangers in real life.

She added to Complex magazine: "For me, it's not a pastime, going out and meeting people and trying to hook up with people. That actually makes me feel disgusting. From a really early age, I was really sensitive to that.

"Getting your flirt on is the best thing in the world, but when it comes to sharing bodily fluids with a person I don't know - no thank you."