Apprantly she was doing a festivial and her skirt hitched up and you can see a bit of what "appears" to be the tip of a willy. The press are claiming she is a hermaphodite but some people think it was an organised pubicity stunt and it's a fake.
http://www.thesun.co.uk/sol/homepage/showbiz/bizarre/2585100/Has-Lady-GaGa-got-a-Poker.html