to be very pleasant and friendly, especially when other people are not expecting you to be.

I was expecting her to be in a foul mood but she was all sweetness and light.

• a baptism by fire
• a baptism of fire
• a bargaining chip
• a basket case
• a battle of nerves
• a battle of wills
• a battle of wits
• ABCs of
• ABCs of something
• a bean counter
• a bear hug
• a beast of burden
• a belly laugh
• a Bible-basher
• abide by
• abide by something
• a big ask
• a big cheese
• a big deal
• a big fish
• a big fish in a small pond
• a big girl's blouse
• a big gun
• a big-head
• a big-mouth