Back the wrong horse:
To support the losing side.
You're backing the wrong horse here. Public opinion strongly supports that issue.
Back To Square One / Back to the Drawing Board
Start all over again.
Well that didn’t work. I guess we’re back to square one.
The bakery offered me a baker’s dozen, so I got one extra bagel. (13 instead of 12.)
Barking Up The Wrong Tree:
Complaining to the wrong person.
He was barking up the wrong tree when he told me I was rude. It was his friend who said something bad!
Beating Around The Bush:
Avoiding the main issue.
Don’t beat around the bush. Tell me what you want.
Bend Over Backwards:
Doing everything possible to help.
I will bend over backwards to make sure the customers are satisfied.
Best of Both Worlds
Getting advantages from two things/places/people.
He has his mother’s looks and brains, but he also has his father’s calm, positive attitude. That’s the best of both worlds!
Between a Rock and a Hard Place:
Stuck between bad options.
I had to either take the 5AM flight, or miss my friend’s wedding. I was between a rock and a hard place.
Someone who thinks they're cooler or more influential than others.
She thinks she's a real big shot with her new haircut.
Blood Is Thicker Than Water:
Family is stronger/closer than anything else.
Remember, we’re family. Blood’s thicker than water.
A way of saying 'I got you!' (with a joke). A roast is an event where a bunch of people (normally comedians) all make harsh jokes about one person, but they joke with love and respect usually.
You're so dumb, you think socialism means partying! Boom roasted!
Brain is wired (How your brain is wired):
How your brain works (is it more creative, practical, etc.).
My brain just isn't wired that way.
Break a Leg:
A way of saying good luck – often used in performances, but also whenever someone needs luck.
Break a leg! I hope your piano performance goes great!
Break Up With
To end a relationship.
She broke up with him for lying.
Breathe Life Into (Breathe New Life Into):
To bring energy or ideas to something.
Kia designs were pretty boring in the past, but since 2006 Peter Schreyer has helped to breathe new life into them.