Kiss my 'S'

Funny story! I was laughing so hard. We, the kids and I, were on our way home from Costco this afternoon. I was just driving just tuning out the noise coming from the backseat. Then I hear, "Kiss my a**." This of course got my attention. I started to listen more. I looked in the rear view mirror and saw Kelson signing the letter 'S' in front of Analise. He was wanting her to kiss his hand signing the letter 'S'. Then Cade joined in with, "Kiss my 'L'." I just started laughing. Obviously Kelson has heard the real thing somewhere else and evidently doesn't know that it means.