| black rider | | | |
| black sheep | | | |
| blame Canada | | | |
| blame game | | | |
| blanket term | | | |
| blank out | | | |
| blare out | | | |
| blast from the past | | | |
| blast off | | | |
| blast out | | | |
| blaze a trail | | | |
| blaze away | | | |
| bleeding edge | | | |
| bleeding-edge | | | |
| bleed red ink | | | |
| blend into the woodwork | | | |
| blessed event | | | |
| bless someone with | | | |
| bless you | | | |
| blimp out | | | |
| blind date | | | |
| blind leading the blind | | | |
| blind with science | | | |
| blink-and-you-miss-it | | | |
| blink first | | | |
| blink of an eye | | | |
| blocking and tackling | | | |
| block out | | | |
| Blondin | | | |
| blood and guts | | | |
| bloodclaat | | | |
| blood in the water | | | |
| blood is thicker than water | | | |
| blood, sweat and tears | | | |
| bloom is off the rose | | | |
| blossom out | | | |
| blot one's copy book | | | |
| blot on the escutcheon | | | |
| blow | | | |
| blow a fuse | | | |
| blow a hole through | | | |
| blow a kiss | | | |
| blow away | | | |
| blow chunks | | | |
| blow hot air | | | |
| blow hot and cold | | | |
| blow me | | | |
| blow me down | | | |
| blow off | | | |
| blow off steam | | | |
| blow one's chance | | | |
| blow one's load | | | |
| blow one's own trumpet | | | |
| blow one's wad | | | |
| blow out of proportion | | | |
| blow out of proportions | | | |
| blow out of the water | | | |
| blow over | | | |
| blow someone's back out | | | |
| blow someone's brains out | | | |
| blow someone's cover | | | |
| blow someone's mind | | | |
| blow the cobwebs away | | | |
| blow the doors off | | | |
| blow the lid off | | | |
| blow the whistle | | | |
| blow this Popsicle stand | | | |
| blow this pop stand | | | |
| blow to kingdom come | | | |
| blow tomahawks | | | |
| blow town | | | |
| blow up in one's face | | | |
| blue-ball | | | |
| bluebird of happiness | | | |
| blue chamber | | | |
| blue devils | | | |
| blue-eyed | | | |
| blue-eyed boy | | | |
| blue moon | | | |
| blue note | | | |
| blue ribbon | | | |
| blue-sky thinking | | | |
| blue state | | | |
| blue wall of silence | | | |
| blur the line | | | |
| blurt out | | | |
| Bob's your uncle | | | |
| body blow | | | |
| body English | | | |
| bogged down | | | |
| bog off | | | |
| boiling frog | | | |
| boiling hot | | | |
| boiling mad | | | |
| boiling point | | | |
| boil over | | | |
| boil up | | | |
| boldly go where no man has gone before | | | |
| bolt bucket | | | |
| bolt from the blue | | | |