After the fight with Pennywise, the Losers Club(Bill, Stan, Richie, Eddie, Mike, Ben and Beverly) were at the barrens, they made a promise to each other. If It comes back, they will come back also. They made the promise by a glass shard and making a line in their palm. When Bill is done, the others were about to go, and Bill was also. But wait.

Bill: Gotta kiss my homies adios.

Bill heavily makes out with Stan