Teach your baby the signs for the words clean and dirty in baby sign language with the following descriptions and videos.
Hold one hand in front of the chest with the palm facing up. Rub the palm of the other hand over the palm of the first hand.
Place the hand under the chin and wiggle the fingers.
Acredolo, Linda & Susan Goodwyn. 2009. Baby signs: How to talk with your baby before your baby can talk, 3rd edn. New York: McGraw Hill.
ASL Pro: http://www.aslpro.com/cgi-bin/aslpro/aslpro.cgi
Beyer, Monica. 2006. Baby talk: A guide to using basic sign language to communicate with your baby. New York: Jeremy P. Tarcher/Penguin.
Signing savvy: Your sign language resource: http://www.signingsavvy.com/