Potty Words

My son, 5 yo, randomly shouts potty words. Sometimes 2-3 in a row, over and over again. When he does that he smiles and looks at us waiting for a reaction. Our reaction usually is like: "Please don't say toilet words, these words make me feel dirty." or "Please , you know mommy doesn't like to hear there words". etc. Needless to say this doesn't work. Please help.