To be under the gun: to be under pressure or stress. 

To be up to one's eyeballs in something: to have a lot of or too much of something.

To try one's hand at something: to try something for the first time. 

To bite off more than you can chew: to commit yourself to more than you can handle.

 To burn the midnight oil: to be awake and doing something late at night.

To buckle down: to dedicate yourself to an activity. To work very hard and seriously at something.

To bite the dust: to break, to be no more. To die. 

To be a pain in the neck: To be an annoyance, a difficulty, a hinderance.

To be between a rock and a hard place: To be in a position where you can't do what you  want to do because you caught between two options that are both difficult or disagreeable.

To not be playing with a full deck: To behave in an illogical or crazy way. To be crazy.

You scratch my back, I'll scratch yours: Said about a situation where two people can benefit from each other help. Each will do the other a favor in order to get what she or he wants from the other person.

To blow up at someone: To suddenly get angey with someone, and yell.

To blow up: To explode. 

To blow something up: To put air into. 

To turn in or to turn in for the night: