There are many things you don't do to people who are best friends. The one thing you should never do is insult one of them. Since they are best friends the other one will make you pay. It was like that for Cyborg and Beast Boy. If you insulted one of them the other would make you pay the price. For example they were at the park one afternoon and a couple walked by. As they passed the man whispered something into his girlfriend's ear.
"Sweetie don't look, i don't want to be near that freak." If he didn't have his super hearing thanks to being half robot he wouldn't have heard it. He looked over to beast boy to see if he had heard them say those offensive words. Strangely he had no reaction on his face. Feeling anger rise in his chest he got up and told beast boy to stay put. Trying to keep his anger in check he marched over to the couple. When he neared them he grabbed the man by the back of his shirt, spun him around, and pinned him to a tree with his fist.
"Listen punk, you got something to say about Beast Boy?" he asked, with his eyes narrowed menacingly.
"No bro i didn't mean it!" the guy said, literally shaking in his shoes as his girlfriend stood behind them unable to do anything.
"That's what i thought. If i hear anything bad like that come out of your mouth again i'll make you pay big time." And with that he let the man go.
"You know you didn't have to do that tin can" Looking behind him he saw Beast Boy standing there.
" I know but no one insults my best friend'" He replied. And with that they went back to the tower and played video gams together.