That would embolden me to intensify the tickling on her butt, taunting her and telling her I won't stop until she says "I have a ticklish ass!" out loud. How would you feel that I caused your wife to say that, as my fingers danced on her butt cheeks, and how would she feel? Also, if I was particularly good at tickling her, maybe better than you, or maybe because it was "taboo" of me to tickle her, and the whole thing made her MORE ticklish when I did it, how would that make you feel? How would she feel about it?