Jump down someone's throat

(become angry with someone)

That's it, Greg! You'd better not come in after midnight again tonight.
I know, dad. You don't have to jump down my throat! I told you that I'd make it home around 11:50.I don't intend to be late! 
Well, you've said that before and in you come at 2:50 in the morning. You can't blame me for getting angry and scolding you. I've got good reason.

Horse of a different color

(quite a different matter)

Eric likes to play jokes on his friends, but he makes sure that nobody is hurt by any of his pranks. A prank that hurts someone is a horse of a different color! Being playful is one thing, but hurting someone by one's prank is quite a different matter.

Take it on the lamb

(flee in a hurry)

Poor Rich has always had his problems with the police. When he found out that they were after him again, he had to take it on the lamb. In order to avoid being caught and thrown in jail, he was forced to flee in a great hurry.

Cat got your Tongue 

(Can't talk?)

Come on, Connie! Tell us what you think about our little ride down the rapids yesterday. 
Well.uh... 
Wasn't it exciting? 
I,uh.. .
What's the matter? Cat got your tongue? 
If you must know, I'm keeping quiet because I was scared out of my wits!

 Get in someone's hair

(bother someone)

- Children.! Would you please stop making so much. noise! And for heaven's sake, pick up your clothes and toys! It's hard enough trying to keep this house clean without your throwing your things all over the place! 
- Clara, I know that the children get in your hair, but you should try not to let it upset you so much. 
- Listen, Jim. I can't help it. The children bother me and make me very angry when they're so noisy and messy.

Shoot off one's mouth

(express one's opinions loudly)

Jim doesn't play tennis very much, but he's always shooting off his mouth about how good he is. Yet he's fooling nobody. Jim is somewhat of a braggart and everyone knows that he gives opinions without knowing all the facts and talks as if he knew everything about the game.