Missy Elliott Dancer Alyson Stoner Didn't Know What 'Work It' Meant

Missy Elliott knows how to put her thing down flip it and reverse it ... but Alyson Stoner says she didn't know the sexual significance behind "Work It" until long after she starred in the music video.

We got Alyson out at LAX after she got back from her highly-regarded dance routine with Missy at the VMAs ... and the dancer and former Disney Channel actress told our guy she was kept in the dark about the song's true meaning for years.

Alyson, now 26, first danced to Missy's provocative hit 17 years ago ... and she says their reunion onstage at the VMAs is easily one of the best moments in the history of the award show.

But, it wasn't until she was older when Alyson says she figured out what Missy was talking about in the lyrics. Kudos to the person who finally filled her in.

It's pretty wild ... Alyson tells us she nearly skipped her audition back in the day because of her sister and parents. But, thanks to a last-minute change of plans, she tried out for a spot in the music video and got the part.