Mr. S is talking to Mr.B

First time telling a joke here. A bit dry but I find it funny

Mr. S is talking to Mr.B Mr.B your bathroom is the same exact size like my bathroom. I need to buy tiles, how many boxes did you get when you did yours?

Mr.B: 20 boxes of tiles!

A week later

Mr.S tells Mr.B : Hey asshole! I did the tiles in my bathroom and I got stuck with 7 extra boxes

Mr.B: Me too