The band's frontman Mark Hoppus shared this adorable snap of Camila and Shawn rocking out backstage.
“Hanging out behind the club on the weekend. @shawnmendes @camila_cabello 🤘” Mark captioned the pic.
The band has a song called "Rock Show" with the lyrics "I fell in love with the girl at the rock show," and just sayin'...that might be what's happening here.
Shawn was in town to play at the Amalie Arena in Tampa and Camila came along to watch.
Earlier that day, they were spotted macking on and chatting animatedly at a local coffee shop, Oxford Exchange.
WATCH: Shawn Mendes and Camila Cabello on a bookstore date
While neither Camila or Shawn have officially confirmed their relationship, the Havana singer recently spoke to music publication Clash about their bond.
“I think I’ve actually known him the longest out of anybody in the music industry — we’ve been in each other’s lives for, like, four or five years, and it’s been really beautiful to kinda grow up together,” Camila said.
“It’s actually a really beautiful feeling to know that this person is always going to be in my life; we’re always going to love each other.”
Whatever this thing is between the two, we're SO here for it and we can't wait to see where they pop up next!
WATCH: Shawn Mendes and Camila Cabello caught on camera making out