When my wife and I were first married, for at least the first couple of years I tickled my mother-in-law half to death on her ribs and feet at least six or eight times. I’ve told stories about this before on TMF and AMT.
I learned to tickle my mother-in-law and forced her to laugh through the degrees while she started out laughing so hard she almost couldn’t talk. Still I made her talk if she wanted any rest at all. I’d pin her down with her arms up under my legs and wriggle by index fingers into her ribs half way down on both sides. The harder she laughed the more fingers I added. By the time I’d have her in silent laugher I would have all my fingers and thumbs on both sides spread as far as I could on her ribs and tummy and just tickle away. Right before she started her silent laughter she would look up at me with that massive smile and shake her head. Then not a sound and she would go into sort of a tickle paralysis. When she would finally be able to take a breath she tried so hard to scream but it came out intense laughter then silent laughter again. It probably seemed to her like a never ending cycle. When a ticklish woman laughs that hard she’s having so much fun there isn’t any way she wanted me to stop. Sometimes when you tickle a woman that way and she is in silent laughter she will lay there with that huge smile for seconds then right before she takes in any tiny bit of air will force out another sixteenth of a laugh. In those cases it’s impossible to tickle as much as she wants. Still, as a son-in-law it’s your duty to try.