SOMEONE has been hitting the gym! And yes, we're talking about DNCE's Joe Jonas. Joe and model Charlotte McKinney are the stars of GUESS' new 2017 underwear campaign, as shown by photos shared this week. 

This gives a whole new meaning to "Body Moves."

The campaign photos, shot by photographer Yu Tsai, show Jonas shirtless -- and some wearing only underwear -- calling attention to his washboard abs.

Joe tells E! of his new campaign shoot that to prep for the pics, he did a lot of boxing with a trainer. He adds, "It's been a fun shoot, and my first time doing [a campaign] in underwear, so it's pretty exciting."

"It can be a weird thing to be sitting there in your underwear being photographed," Jonas admitted to E!, "but overall I had a blast."

I mean...

Of course, this isn't the first time a Jonas brother has participated in a sexy underwear campaign. #TBT to Nick Jonas' Calvin Klein campaign. 

Which JoBro wore it better?