James Franco's Bar Mitzvah: 'GMA' Goes Behind the Scenes

VIDEO: Seth Rogen Throws James Franco a Bar MitzvahPlayABCNews.com
WATCH Seth Rogen Throws James Franco a Bar Mitzvah

Actor James Franco has officially become a man, celebrating his adulthood at his huge bar mitzvah bash in Hollywood Saturday.

Friend and fellow actor Seth Rogen threw the star-studded bar mitzvah for a good cause, the fourth annual Hilarity for Charity event to help raise awareness for Alzheimer’s disease.

"My mother was diagnosed with early onset Alzheimer's at 55 years old," Rogen’s wife, Lauren Miller Rogen, a co-host of the evening, told ABC News.

But why make a man of Franco as the annual Hilarity for Charity variety show?

"He's Jewish," Rogen said. "He mentioned to me that he never had a bar mitzvah, that he always wanted one. It's a starting over point. So everything he's done up until now doesn't count."

But, of course, no coming-of-age party is complete without a personal performance by Miley Cyrus, every 13-year-old bar mitzvah boy's dream, only Franco is 37 years old.

Cyrus, 22, was dressed to impress in a shiny blue leotard, enormous Star of David accessory and silver cuff bracelets emblazoned with the Star of David, as well.

Actor Jeff Goldblum made an appearance also, performing a fake medical procedure on stage dressed as a rabbi.

Franco actually "got bar mitzvahed" two weeks ago, Instagramming this photo of the special ceremony.

This year's Hilarity for Charity variety show, "James Franco's Bar Mitzvah," benefiting the Alzheimer’s Association, was presented by Funny or Die and go90.

The event not only made a man out of Franco, but raised $2.5 million in the process.

Mazel tov, James.