I love when they ask the rikishi to goof around. They are competitive, so the reactions are always great. Here Ura, near the end, just casually gets 90kg (198 lbs) when he squeezes the grip tester. Then when everyone is surprised, he knows he can do better and does :) Some of the others cheat or even refuse to show what they got. Grabbing the belt is a big part of sumo, but I don't know how much grip strength really goes into it, but it's fun to watch adult men just get competitive and laugh at the results.