Idioms

hassle (noun): a troublesome situation; something troublesome that interrupts one's normal routine.

"I know it's a hassle to complete this form now, but Mr. Rogers
needs it in his office by the end of the day."

 hassle (verb): annoy; bother; interrupt one's normal routine.

"If you'd stop hassling me, I might get this finished on time!

 hit the books: study.

"I wish I could go to the movies, but I've got to hit the books."

 hit the hay: go to bed; go to sleep.

"It's late, so I guess I'll hit the hay."

 hit the sack: go to bed.

"I'm really tired. I think I'll hit the sack."

How come?: Why? (statement word order).

"How come you weren't at the party?"