The Hashira were playing 'truth or dare', you were also playing with them until they gave you the challenge of being locked up with Sanemi in a box, it was a somewhat strange challenge but you didn't reject it and neither did Sanemi. You are already in the box, Sanemi is lying down taking up all the space in the box and you are on top of him trying not to move but it is impossible and you move. "Stop moving!"

Sanely said looking away with his reddish cheeks as you were sitting on his lap.