Aiki bowling !
You do not need to go off the mat to play bowling. It is quite frequent wile doing a randori. We were several groups of three, two uke and a tori, and it was ushiro ryokata dori kokyu nage. The tori (a 1st dan) threw me a little violently, but I did not mind : I had got used to do my ukemi on instinct, but a little blindly, and I rolled into the third person in our group. It was real bowling ! I was not hurt, but he needed a little more time to recover. So randori can be something dangerous !