John Stamos is treating "Full House" fans to a musical update they never expected.
The 60-year-old actor teamed up with former "American Idol" contestant Jax to record a sweet new lullaby version of "Forever," the Beach Boys song his "Full House" character, Uncle Jesse, performed multiple times on the ABC sitcom.
Stamos sang the song as the frontman of the fictional band Jesse & the Rippers. He also memorably crooned it during his character's 1991 wedding to Rebecca (Lori Loughlin).
More than two decades later, Stamos reprised "Forever" for the debut episode of the Netflix revival "Fuller House" in 2016.
In real life, Stamos recorded the song with the Beach Boys in 1992. The actor has performed with the classic rock band many times over the years.
The '90s version of "Forever" was itself an update: An earlier rendition of "Forever," which was written by late Beach Boys member Dennis Wilson and his songwriting partner Gregg Jakobson, first appeared on the band's 1970 album, "Sunflower.
In his collaboration with Jax, Stamos has turned the ethereal song into an even more harmony-drenched tune for little ones to enjoy.
The actor, who shares a son, Billy, 5, with wife Caitlin McHugh Stamos, teased the new rendition in a cute video alongside Jax earlier this week on Instagram.
The short clip shows the two musicians taking a break from recording when Stamos presents Jax with a vintage Uncle Jesse doll.
The actor also demonstrates for Jax how easy it is for a rock star to tear his onstage clothing while wearing what he calls a "rip-away" shirt.
"My whole teenage dreams just came true with that moment," Jax says, laughing.
"My mom's going to be so pissed she wasn't here for the last 30 seconds of my life," she adds.
Holding up the Uncle Jesse doll, Jax quips, "This is probably the most valuable thing in our house at this point.
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Stamos wrote in the caption of his video, "I had too much fun working with @jax on this new dreamy version of 'Forever,' available to stream *this* Friday."
Jax responded in the comments of Stamos' post, writing, "Hahahahahaahaha omg uncle Jesse just being uncle Jesse."
