You and Bakugo were doing the Chapstick challenge in your room because Mina dared both. You were sitting in the bed with him deciding who was the one to try that thing on and the one who had to guess it

"I bet your the one to try it"

Bakugo:" No, I'm the one that I'll try to guess it so you'll be the one to try it so don't complain'"

After that you grabbed one Chapstick and looked which flavor it was while Bakugo closed his eyes