"Adding" joke

One day a boy named Jonny was learnig out to add. When he got home from school, he started to do his homework. So he said out loud,"
2+2, o that sun of a bitch is
4. 3+3, o that sun of a bitch is
6."
As Johnny's mom was walking past his bedroom and heard what he was saying. So his mother called the school asking to speak to Johnny's teacher. She said,"
Are you teaching my son to say bad words while he is doing his homework?"
"
No."
"
Well my little Johnny is saying 2+2 o that sun of a bitch is
4."
Johnny's teacher says,"
No no no! I taught him to say 2+2 o that sum of which is 4!"