Motley Crue bassist Nikki Sixx celebrated his 53rd birthday on Sunday, Dec. 11. We know, the man born Frank Feranna doesn't look it. Even with all that hard living, rock 'n' roll has kept him fashionable and young at heart.

But 'tis true, and it didn't go by unnoticed. Joe Elliott, frontman for the Crue's current tourmates and fellow '80s superstars Def Leppard, was like that friend, you know, the one who's more than happy to remind fans that it was Sixx's big day. At their performance in Manchester, England, Elliott popped on stage during the Crue's set to lead the crowd in a rousing rendition of 'Happy Birthday.'

Sixx was in the middle of saying "We are Motley mother f---ing Crue" when Elliott appeared on stage to get the song started with a big hug, which is also how it ended.

As Elliott was walking off stage afterwards, Sixx referred to him as "Joe f---ing Elliott." Everyone had a middle name of "f---king" on Sunday night, thanks to Nikki Sixx. But hey, it was Sixx's f---ing birthday and he'll call people whatever the f--- he wants.

Watch Joe Elliott Lead the Crowd in Singing 'Happy Birthday' to Nikki Sixx