to be not very good or not as good as you would like.

And if you think my driving leaves something to be desired, his driving is even worse!

• a ballpark estimate
• a ballpark figure
• a balls-up
• a banana republic
• a banana skin
• a Band-Aid
• a bang up job
• 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