[He was opening his mouth to say "I'm good" or something along those lines and instead Shiro goes for the kill and what comes out of his throat is an undignified squawk, that devolves into involuntary laughter and a loud:]
Wait, no-- Shiro!
[But he's trapped under him and the boat doesn't exactly give any room so as he struggles, he squirms at the waist, the movement kind of helplessly automatic even as his brain is already trying to shoot out warning signs for him to stop. He doesn't. The laughter is still getting away from him, trying to catch Shiro's wrist.]