My parents have a super old milkshake/malt maker that is ungrounded. It's the type that has a long rotating metal stick on the main body and a metal cup that hooks onto the main body. You put your ingredients in the cup, stick it on so the metal stick is in the middle of the cup, flip the motor on and move the cup around until your milkshake is done.
At the time, they had a built-in stovetop that had a metal huddee ring around it. I was making a milkshake, one hand on the cup to steady/move it. I moved to rest one hand on the counter and put it on the huddee ring instead. The shock wasn't super strong, but it was enough to blank my mind for a few seconds. Then I realized, oh! I'd better move my hand. It was actually kind of pleasant, but I wouldn't do it again.