'Firework' sensation Katy Perry has opened up about some of her more private habits in a new interview with Us Weekly. 

Speaking to the publication about her personal life, she explained that she has obsessive compulsive tendencies and laughed that even the letters 'OCD' bother her because they're not in order:

"I'm all about vitamins and supplements. I'm so OCD that I wish the letters OCD were in alphabetical order: CDO."

During the question and answer session with the magazine, she also confessed that she's a big fan of fast food and has particular favourites:

"Everyone in my life seems to think I'm a hoarder, but if you ask me, I'm a collector! My comfort food is chicken nuggets, but only the boot-shaped ones. My favourite ice cream is Cold Stone Creamery's Birthday Cake Remix."