bend/stretch the rules

to do something or to allow someone to do something which is not usually allowed.

We don't usually let students take books away, but I'm willing to bend the rules on this occasion.

• the big picture
• the big smoke
• the big time
• the bird has flown.
• the birds and the bees
• the biter bit
• the biter is bit
• the bitter fruits
• the black sheep
• the black sheep of the family
• the blind leading the blind
• the blue blazes
• the boot is on the other foot
• the bottom drops out of the market
• the bottom falls out of the market
• the bottom fell out
• the bottom fell out of
• the bottom fell out of something
• the bottom line
• the bottom of the barrel
• the bottom of the heap
• the bottom of the hour
• the bottom of the ladder
• the boys in blue
• the brains behind