Troubled singer Britney Spears astonished mother-of-three Heidi Klum recently - by showing the supermodel the proper way to put a diaper on a baby. Klum was surprised when Spears, who is fighting reports she's a bad mum amid her custody battle with ex-husband Kevin Federline, arrived uninvited at her Halloween (31Oct07) party at Los Angeles venue Green Door. And Spears left Klum speechless when she offered up her diaper-changing expertise. Klum says, "We were talking about babies and diapers and she explained to me a lot of things about diapers I that didn't know. "You know these sticky things on the side? I never knew that they were there. To close them in the front, I was always putting string around. I had no idea. "It's very clever. I learned a lot of things."