Castle of Sand Puns

I was leaving for work and my son said he and my wife were going to build a sand castle in the backyard. I told him to make sure she took a picture of it because I wanted to see it. He replied "do you want her to... sand it to you?" (with the correct pause and emphasis). Then he started giggling. As I walked the house gathering my things for work, he followed me, repeating the joke another three times.