Your wife gave you socks for Christmas and you smiled happily and kissed her? You, my friend, know how to dissimulate — that is, cover up your true feelings. Unless you happen to really, really like socks.
Sometimes confused with dissimilar, meaning "not alike", or "different," or a form of simulate, meaning "to pretend to do or feel something." Being able to dissimulate is a useful trick, not just if your wife gives you socks. After all, the whole political process depends on it. As Louis XI once said, "He who knows not how to dissimulate, can not reign." Wikipedia would probably agree with that.