Here's Stacey -- a former Team USA gymnast -- and Simone having an average day at the office ... seeing if Ervin can box jump the entire height of his boo -- who he's been IG official with since last summer.
Dude clears it with ease -- but says Biles was "only a little impressed." (WHAT!)
Yeah, she's only 4'9'' ... but that's some damn impressive ups.
Fun fact: Stacey's been flyin' around the ring in hopes of a career in WWE ... and after seeing this, we're pretty sure he can cut it.