Heidi Klum celebrated her 40th birthday on Saturday (01Jun13) with a hat party. The German model donned a sparkly top hat for her special day and posted a photo of herself and guests posing with hat-shaped cakes on Twitter.com. All the revellers, including fellow model and reality TV star Yolanda Foster, were wearing hats. Earlier on Saturday, she tweeted thanks to fans and friends for "all the wishes, flowers, balloons and gifts," and she closed out the big day with the simple message: "Fun day. Thank you."