The Avalon Hollywood was shaking with laughter April 25, as comedians and supporters gathered for Seth Rogen’s Hilarity for Charity fundraiser, which featured lewd songs, cracks about Reese Witherspoon, a live auction and — yes — the Backstreet Boys.

Created by Rogen and wife Lauren Miller, Hilarity raises money and awareness for Alzheimer’s, with Thursday’s event producing more than $400,000.

Celebs came in droves for the event, which was stylized like any stoner’s dream house party. That included walking a green carpet on Vine and then ducking inside for kegs, red wine and tacos. Outside on the sidewalk, fans clamored to snag photos and sound bites from stars like Jack Black and Rob Riggle, who engaged with one fan in a brief conversation about the importance — or lack thereof — of subtitles.

“I don’t mind them if it’s the right movie,” he said with a grin. “But if it’s a bad movie and I have to read on top of it?” He made a fart sound and gave a thumbs-down.

Inside, guests partied like sardines, snagged raffle tickets and purchased T-shirts that read “Don’t Forget.”

Sadie & the Blue Eyed Devils kicked off the night’s festivities, followed by David Krumholtz, who sang the Hilarity for Charity theme song and introduced the night’s host, Rogen.

Samuel L. Jackson made a surprise appearance, lauding Rogen’s cause and sharing that his mother and multiple members of his family had suffered from the disease. He lightened the mood a bit, saying, “One day you could wake up and not know who the fuck you are,” before introducing the next act.

Comedian Kevin Hart followed up, demanding people to “stop judging me for my DUI.” He claimed he was very compliant with the cops; whereas, other stars — namely, Witherspoon — were not for their respective arrests.

Comedy folk duo Garfunkel and Oates performed a quick, love song-inspired set, which included one ditty about entering your 30s and another about anal sex. The girls crooned, “I’ve emptied my bowels and laid out some towels,” before leaving the stage to thunderous applause.

John Mulaney, Ken Marino, Justin Willman, Mindy Kaling and Riggle gave brief perfs too. The latter boasted his charitable acts: “I make Bono look like fucking Adolf Hitler, and I make Mother Theresa look like a cheap, tea-bagging hooker.” He then proceeded to fire a T-shirt gun.

Billy Eichner helped auction off a glass of water — yes, for $900 — and other more glam things. “This is a chance to feel as entitled as Reese Witherspoon, people,” he coaxed.

All good things eventually came to an end, though, but not before the Backstreet Boys hit the stage. Everybody was dancing, including Rogen who jumped onstage and showed off some Backstreet moves of his own.