When: May 2010
Chelsea played Joe's girlfriend on the JONAS TV show, which meant the two shared an onscreen kiss. They were spotted shopping and walking around L.A. but they seem to have gone no further than BFF. And BFF means "best friends forever," not something dirty you could easily make up with those letters.
Smash probability: There was no friends-with-benefits situation brewing here. Otherwise, they would've had more chemistry on screen.