Billie Joe Armstrong and his wife on their way to Mark Zuckerberg's wedding, NBD.

You know what's cooler than a million dollars? No, seriously: Billie Joe Armstrong playing at your wedding. In pretty much the best wedding present ever, the Green Day frontman made an appearance at Facebook founder Mark Zuckerberg and girlfriend Priscilla Chan's surprise nuptials over the weekend to play 21st Century Breakdown ballad "Last Night on Earth." The touching moment was captured on video from behind bushes outside the wedding (not creepy at all), so you'll have to imagine Billie Joe's adorable facial expressions as he dedicates the acoustic track to his own wife.

"Mark wanted me to play this song… this song is one that I wrote for my wife of 18 years -- it better be for her, or I’d be in deep trouble," he joked before introducing "Last Night on Earth." Aww. True love! Since our invite to the wedding obviously got lost in our Facebook inbox, Zuckerberg should definitely make it up to us by posting the full video (from the other side of the hedge, please!) on his wall ASAP. In the meantime, we'll cross our fingers that it never gets too, um, complicated for these two crazy kids. Luckily, any couple endorsed by Billie Joe is probably going to work it out.

Photo credit: Pacific Coast News