Gaga, real name Stefani Germanotta, celebrated turning 25 with her good friends and family - including her boyfriend Luc Carl, Adam Lambert and Kate Hudson at Los Angeles's LA Cita Mexican restaurant - and was given several saucy gifts.
A source told British newspaper the Daily Mirror: 'Gaga got diamonds from one anonymous guest while another had a sex doll made for her - its piece de resistance was a huge penis.'
The insider added: 'Gaga, who treated her tequila-swigging guests to a tipsy rendition of Born This Way backed by the restaurant band, was on serious form.
'Adam Lambert got a little over-excited while dancing and bashed his head on the ceiling. And Gaga's mum Cynthia looked red-faced at times - she kept muttering, 'Stefani!' under her breath.'