Back seat driver
Person who like to involve in other's business.
Back to square one
Back to the starting point again
Back to the wall
In a ready-to-fight situation due to no other way to escape.
Backup the wrong horse
Support the wrong person, team or side.
Person who is different, in a negative way, from the group.
Bad hair day
A day which everything seem to go wrong.
Bag of bones
Very skinny person/ animal.
Beggar on horseback
Poor person who acting arrogant when become rich or achieve only small thing.
Already made decision, agreed on something
Certainly, No doubt
Birds of a feather flock together
The same type of people or people who like to do the same thing
Blessing in disguise
Good thing that you never reconginize at the first place
Kill by gun shot
Already finish, forget
Bound to do
Likely to happen / Likely to do something
Bottom of the barrel
The worst part of the group / organization
Break a leg
Break into tears
Suddenly yell out (either sad or happy)
Break the ice
Talking or doing things to release pressure or to make listeners relax
By and large
Generally, In all case.
Specific character attached to someone from their family or country