Baby oil is the best thing to use, IMHO. A thing I discovered which a certain, missed friend here (thanks Normie!) told me was that a good strategy is to use baby oil or a special foot care/moisturizer, then have the pair of feet wear a pair of socks (preferably thickish) for about 30 minutes to an hour. Feet come out super soft after that time and that equals super ticklishness, but if you want the quick fix, use baby oil! 🙂