True. More often than not, if I start babbling incoherently, it's because I would do literally anything for mercy. In the case of our hypothetical threesome, wifey joked once that she wanted to see if I'd lick a guy's feet, suck his toes or kiss his stomach or something like that just to make it all stop. (she wouldn't make me suck his dick, or so she says). If that ain't broken, I don't know what is.
You sometimes get so annoyed by being tickled that you groan or growl rather than give your tormentor the satisfaction of hearing you laugh.