Electra Mustaine celebrated her 22nd birthday on Tuesday night at the Zenith in Paris by jamming with her dad on stage. Did we mention that he's Dave Mustaine of Megadeth and they collaborated on a duet of the band's "ÀTout Le Monde?" Well, they did and it was a very special night for the model/singer, who chronicled the special night in an Instagram and a series of tweets in which she called it the "Biggest & best bday party... ever!"