Webster's New World: American Idioms Handbook

“The little boy couldn’t wait and accidentally went to the bathroom in his pants.”

urinate and defecate.

American English does not use the term loo for toilet.

the head

the can

the john

example, native speakers of American English prefer not to use the specific word “toilet.” So, rather than say “Where is the toilet,” which sounds a little crude, it’s much more common and polite to say:

Where’s the men’s room (or ladies’ room)? (said in public places)
I need to find a restroom. (said in public places)
May I use your bathroom? (said in a private home)

up with the chickens

up at the crack of dawn

Staying up late to work on a project is described as burning the midnight oil

Grammar Note: Don’t say “I slept late last night.” This doesn’t make sense, because the idiom sleep late means to sleep later than usual in the morning! Instead you can say “I stayed up late,” “I went to sleep late,” or “I went to bed late.”

o beddy-bye or go nighty-night