Meghan Trainor and Charlie Puth seemed to have taken their duet "Marvin Gaye" to heart at the 2015 American Music Awards.The two shared the stage to sing Puth's track, which has him singing "Let's Marvin Gaye and get it on," and also to share a kiss. A very, very long kiss.After finishing the last line of the track, the two unexpectedly locked lips and kept going for a good few seconds as the crowd looked on. The camera cut away before the kissing even ended.Luke Bryan even joked about the pair's make-out session as he won the next award, Favorite Male Artist — Country. "It even went into the commercial break." Somehow, we almost believe him.But before you go spreading rumors that the two singers are kissing buddies off stage as well as on, it should be noted that this isn't the first time the two have made out for the cameras. As MTV reported, the two shared a very long kiss for the "Marvin Gaye" music video — in front of Puth's parents.So yeah, this is kind of their thing.