1. rat people out
Where I come from, you don't rat on your friends.
2. cut in line
I get annoyed when people cut in line.
3. have an affair
I felt bad for Joan when Jack started to have an affair last year.
4. stab someone in the back
He will say nice things to your face and then stab you in the back.
5. swear all the time
It's wrong to swear and shout.
6. tell on people
He often tells on his classmates.
7. stand somebody up
I've been stood up!
8. break your promise
How could you break your promise?
9. be ungrateful
After all I had done, she was still ungrateful.