Dave Grohl has compared Kim Kardashian West's butt to two space hoppers.

The Foo Fighters frontman has admitted the star's derriere - which has been the talk of the internet this week after her naked shoot in Paper Magazine, including a shot of her oiled behind, was unveiled - reminded him of an inflatable child's play-thing, a Hippity Hop, also known as a space hopper, because of its size.

He explained: ''I used to have this thing when I was a kid called a Hippity Hop.

''It's like this big inflatable thing with handles and you just bounce around your yard, it's kind of like a Hippity Hop. It's actually two Hippity Hops!''

The singer also admitted he struggles to see how the raven-haired beauty sits down every day due to the size of her posterior.

He said: ''It's the biggest, most unreasonable butt you've ever seen in your life.

''I don't know how she can sit down?''

The 45-year-old rocker - who has three daughters, Violet Maye, eight, Harper Willow, five and three-month-old Ophelia Saint with his wife, Jordyn Blum - also recalled an experience when he bumped into the 'Keeping Up With the Kardashians' star, confessing he was mesmerised by her behind.

Speaking on BBC Radio 1, he said: ''There was once when I was taking my kids to their ballet class and she was at some crazy gym that was next door.

''It was one of those military gyms which was like, 'I want to make your ass huge!' and she walked by and it is like an optical illusion.''