A friend of mine asked me a question about a BC I was not really able to answer. I mean I replied but I also told him to double-check on it... Here is what he asked. He used a rented BCD. When he entered the water the waist belt (strap) slid up moving from his waist up to his chest and the shoulder straps that were supposed to sit ON his shoulders also moved up and were touching his ears when the weight belt dragged him down. He tried pulling the entire BC down, fastened the waist strap as tight as he could and dove. It did not bother him much under water though. However, upon ascending the story repeated. The inflated BCD slid up and he was practically hanging on the waist strap that actually moved to under his arm pits and the shoulder belts were "standing" a way above his ears.

It must've been the funniest view ever!
I suggested three possible ideas: 1.) BCD was too big for him. 2.) He did not properly fasten his waist belt. 3.) BCD's waist belt was too loose for him and could have required adjustment.
Has anybody seen anything like that? Any more suggestions?