Katy Perry: I behave like my grandmother

Katy Perry fears she's turning into her 91-year-old grandmother as she eats "1p store biscuits and half a banana" for breakfast.

The songstress discussed her family in an interview with BBC radio station Radio 1 on Monday morning.

Although Katy loves her grandmother, she fears she's following in her footsteps and getting old before her time. The 27-year-old beauty has already adopted some of her bad habits.

"She's 91 now, almost 92. She buys this Chinese-looking biscuits at the 1p store and she has two of them and half a banana for breakfast, and all of a sudden I've started doing the same thing," she laughed.

"She's really cool. She throws gang signs. She doesn't care about any of my stuff. She's just normal. She kinda rolled her eyes [at the blue hair]. Older ladies, as much as we respect them, should note that their hair goes blue or purple."

Katy also addressed rumours about her collaborating with friend and fellow pop star Rihanna.

The singer is reluctant to rush into anything as she wants the musical hook-up to be of epic proportions.

"We've collaborated on a lot of things, but just not songs yet. It's one of those things that's got so much build up that we have to deliver. I want it to be like that Eurythmics and Aretha Franklin song Sisters Are Doin' It for Themselves, not like [Shakira and Beyonce Knowles'] Beautiful Liar," she explained.

"But I definitely want to do something that is so iconic. [Rihanna's] kind of busy too. We're both busy but we planted the seed two years ago. How disappointed would you be if that song came out and it's no good? Sometimes you have to wait for greatness."

Katy is gearing up to release a part-biopic, part-concert film to be shown in 3D entitled Katy Perry: Part of Me to be released this summer. She has revealed watching the movie will be "basically like being in bed with me".

Katy is also currently promoting Teenage Dream: The Complete Confection.

She hopes to connect with her fans.

"It's funny, I always told my listeners that I would always be honest in my songs. I think that is what everyone wants to hear, they want to hear the truth, and especially when it's concerning a problem," she said.

"We all think out problems are unique, like no-one could feel this c**ppy, but then we listen to a song and we're like, 'Thank you, someone feels the same.'

"[The process is] always cathartic, but it's definitely like I'm pushing something out. It steeps to this breaking point, and instead of going to this bad place, I just free verse."