My 3-year-old has begun doing a couple of things that are socially uncomfortable. For one, he's giving mouth-to-mouth kisses; for another, he's kissing people on whatever body part happens to be within reach. I've tried saying "only on the cheek", and he says "why?", and I say "because that's where people like to be kissed". But I haven't noticed any change in the behavior yet.

Any suggestions?