24 Moby Thesaurus words for "tongue in cheek": casuistic, casuistry, crossed fingers, dishonest, disingenuous, disingenuousness, emptiness, empty, hollow, hollow mockery, hollowness, insincere, insincerity, jesuitic, jesuitry, mealymouthed, mockery, sophistry, uncandid, uncandidness, uncandor, unfrank, unfrankness, unserious

Source: Moby Thesaurus II by Grady Ward, 1.0