I guess its normal to go into a sort of paralysis when a ball is in the girl's mouth. That tongue swishing can really hurt and when it rubs against her teeth, well it hurts pretty bad. If she sucks it really hard though, I start to get teary eyed.
I don't think its possible to cum from just ball sucking, but then again anything is possible. I believe its a nice jester from a woman to a man. I especially love when they just plain play with them, but that belongs to another post. ^_^