In deep water
The company's in deep water now that the tax inspectors have decided to check over the accounts.
Many families are in deep water because of the mortgage crisis, and some might even lose their homes.
Barry was in deep water after he was caught stealing office supplies.
Meaning: If you're in deep water, you're in some sort of trouble or in a difficult situation.
Etymology: Probably metaphorical, and related to the fact that deep water can be very dangerous, especially if someone can't swim.
Get off on the wrong foot
I got off on the wrong foot in my new job when I forgot to pass on an important message to the boss.
Helen got off on the wrong foot in her performance when she forgot the first few words of the song.
Jack and Sarah got off on the wrong foot on their holiday when they missed their plane.
Meaning: If you get off on the wrong foot, you start something poorly, or begin with a mistake.
Etymology: The foot in this term represents the first step or phase of an action.
Half-baked
The trouble with Mick is that some of his ideas are good, but a lot of them are half-baked and can't be used.
Editing a student newspaper is difficult because I get a lot of half-baked poems and stories from the kids, and they get upset if I don't publish them.
Simons is always coming up with half-baked ideas for something to do, last week he said he wanted to go skydiving.
Meaning: If something is half-baked, it hasn't been properly thought out or planned.
Etymology: Probably metaphorical, from the fact that if something is being cooked in an oven, or baked, it'll be half-baked if it's taken out of the oven too soon, and it won't be worth eating.