I did the equipment exchange buddy breathing with my instructor, I had to don/ doff my own equipment handing him each piece while handing off my reg to simulate buddy breathing, he intentionally gave me my reg upside down every time trying to panic me, unsuccessfully. Also wore different weight so he dropped his weight belt and had me hold him from floating off, then hand him my belt and still keep a grip on his BC, all still getting water in my upside down reg, a lot of things going on rapidly