If your are energetic and vigorous, you are feeling your oats.

If something has gone for a ball of chalk, it has gone terribly wrong.

If you shake in your boots, you are terrified.
(Quake/cower in your boots are also used. You can also shake in your shoes.)

If someone tells you to fill your boots, they mean that you can help yourself to as much as you want of something.

If people are up in arms, they are complaining or protesting angrily about something.

If someone can dish it out but can't take it, they criticise people freely but dislike being criticised.

Rivers of indicates a large amount of moving liquid, like rivers of sweat running down someone's brow. It can be figurative like saying that rivers of blood will flow to indicate serious conflict.

It something doesn't amount to a hill of beans, it is worthless. 

If you catch someone on the hop, you do something when they are not expecting it and are not ready.

If something is the height of folly, it is completely ridiculous and will end up badly.