Katy Perry has told UK Elle that she is proud of the fact her friendship with British Twilight hunk, Robert Pattinson, is purely platonic, and that it will always remain that way because she farts in front of him.

Speaking in the September issue, the 'Part of Me ' singer singer said:

"He's my bud, I'm like his big sister. We just hang out.

"OK, so here's the proof there was never anything going on with me and Robert Pattinson, I fart in front of him. Properly fart. And I never, ever fart in front of a man I am dating. That's a rule."

Perry who was married to British comedian and actor, Russell Brand, revealed that she once went as far as to tell Pattinson:

"'One of the things I'm most proud of is not sleeping with you, Robert'. And that's true."

Perry has even texted Kristen Stewart, Pattinson's ex, to hell her not to worry about their friendship becoming physical:

"I sent her a text message saying: 'I know you've seen all this stuff, but you know I would never disrespect you. I'm not that person. I'm just trying to be a friend to him, but it is unfortunate that I do have a set of tits."

Perry is currently dating American singer-songwriter, John Mayer.

Watch Katy Perry and Cheryl Cole on The Graham Norton Show (2012) below: