Is it normal for a teacher to say this?

i'm part of this group that pretty much has all races in it. We got Asian, Hispanic, African american, etc. The whole 9 yards.

We usually talk about sex, racism, drugs and alcohol. Especially racism since, we made jokes and crap but nobody gets offended because were all friends.

One day, We were at school at our usual hangout spot during lunch. It was next to the door to the other hallways. We talked about what we usually talked about. And these two new people came. We talked to them for a while, then they went to the door and opened it and shouted words like orgasm. They left. About 1 or 2 minutes later a teacher comes through the door and yells at us.
He said:
"Which one of you stupid retards is saying shit down the hallway? You people talk about race, sex, and alcohol and have the same damn conversations everyday. Its sick and nasty, you people need mental help."

We didn't know he listened to our conversations everyday. He storms off. Then the entire group bursts out laughing all the way to our next class. That Teacher thinks were bad, he needed to listen to the conversation of the other groups of this school. Were not that bad.