Angelina Pivarnick lived every millennial's dream by joining Backstreet Boys' AJ McLean and *NSYNC's Joey Fatone for a show ... and yes, she rocked out like any of us would.

TMZ has obtained video featuring the "Jersey Shore" star enjoying a boy band-filled gig in Newark, NJ last week ... where Joey and AJ teamed up for a concert at the New Jersey Performing Arts Center, and where Angelina was front and center as a megafan.

It seems her adoration for the fellas paid off ... 'cause they brought her onstage to sing and dance ... and she did plenty of both.

Angelina proved she's just like any other Backstreet/*NSYNC fangirl -- boldly belting along to the duo's rendition of "It's Gonna Be Me" ... happily filming selfie videos with fellow fans, too.

Folks are feeling as nostalgic as ever on this front ... especially since *NSYNC recently reunited onstage during Justin Timberlake's free, one-night-only concert in L.A. earlier this month. The group performed their new collab, "Paradise," which is featured on JT's sixth studio album ... and it's left diehards pining for a straight-up real reunion.

Of course, when we caught up with Joey at LAX recently, he kinda shut down any notion of a reunion happening anytime soon ... making it clear no new album is coming from *NSYNC.