We have to wonder if he's the same guy appearing to kiss the Mean Girls' actress' back in this earlier Instagram post from January -- a post she captioned simply with the prayer hands emoji.
Either way, there's no word yet on the identity of the owner of the abs. The 29-year-old's last public relationship was with DJ Samantha Ronson, but she's previously been linked with celebrities including Wilmer Valderrama -- whom she dated in 2004. And then there was the time she was James Franco's muse.
ET reached out to Lohan's reps to find out the answer to this hunky mystery and we'll update if we hear back.
Uncovered skin is not that unusual on The Canyons' actress’ Instagram. Earlier this year she commemorated a volcanic cleanse in Costa Rica with a mud-covered topless pose on her account. Sadly, Mystery Abs was not also pictured.