Megadeth's Dave Mustaine celebrated his 51st birthday on Sept. 13 by playing a concert to a packed house in Buenos Aires, Argentina. After playing their last song of the night, Mustaine was surprised with a birthday cake onstage by two lovely ladies, while the crowd sang 'Happy Birthday' to the legendary frontman in both English and Spanish.

Megadeth founding member and bassist David Ellefson led the crowd in singing 'Happy Birthday' while Mustaine (sort of) blew out his birthday candles. Mustaine took a quick taste of the cake, but in the spirit of sharing, threw the huge cake into the enthralled audience, where pastry and frosting was surely gobbled down by all.

Mustaine addressed the crowd, "I want to thank you all for coming out tonight. I hope you had a great f---ing time, 'cuz we sure did. I love you, Argentina!"

The frontman later tweeted, "Thursday night was one of the best birthday parties I've ever had! Argentina… Thank you!!!"

In other Mustaine news, the Argentinian gig was also home to a strange incident where the frontman nearly toppled over while standing onstage. The random and peculiar loss of balance was captured on film (see below) before Mustaine said to the crowd, "Got a little carried away."

Check out both Mustaine's birthday celebration and battle with equilibrium in the videos below.

Argentinia Crowd Sings 'Happy Birthday' to Dave Mustaine
Dave Mustaine Loses His Balance Onstage