| bolt to the bran | | | |
| bomb out | | | |
| bone-crunching | | | |
| bone-deep | | | |
| bone dry | | | |
| bone-dry | | | |
| bone hard | | | |
| bone-idle | | | |
| bone in her teeth | | | |
| bone in the throat | | | |
| bone of contention | | | |
| bone-shaking | | | |
| booby prize | | | |
| boogie on down | | | |
| book burning | | | |
| book dumping | | | |
| book in | | | |
| book-length | | | |
| boon and bane | | | |
| boot camp | | | |
| booze can | | | |
| bop the bishop | | | |
| bored out of one's mind | | | |
| bored shitless | | | |
| borganism | | | |
| born and bred | | | |
| born in a barn | | | |
| born with a silver spoon in one's mouth | | | |
| borrowed time | | | |
| borrow trouble | | | |
| bottle away | | | |
| bottle up | | | |
| bottom dollar | | | |
| bottom fishing | | | |
| bottom line | | | |
| bottom-line | | | |
| bottom of the line | | | |
| bottom of the ninth | | | |
| bottom out | | | |
| bottom the house | | | |
| bounce back | | | |
| bounce off | | | |
| bounce off the walls | | | |
| bouquets and brickbats | | | |
| bow and scrape | | | |
| bow down | | | |
| bow down before the porcelain god | | | |
| bowl a googly | | | |
| bow-legged wi' brass | | | |
| bowl of cherries | | | |
| bowl over | | | |
| bowl up | | | |
| bow out | | | |
| box clever | | | |
| box oneself into a corner | | | |
| box seat | | | |
| box someone's ears | | | |
| box the compass | | | |
| boy howdy | | | |
| boy in the boat | | | |
| boys and girls | | | |
| boys and their toys | | | |
| boy toy | | | |
| brace of shakes | | | |
| bragging rights | | | |
| brain bucket | | | |
| brain candy | | | |
| brain drain | | | |
| brainpower | | | |
| brain surgeon | | | |
| brain surgery | | | |
| branch off | | | |
| branch out | | | |
| brass ceiling | | | |
| brassed off | | | |
| brass farthing | | | |
| brass monkey | | | |
| brass monkeys | | | |
| brass neck | | | |
| brass-neck | | | |
| brass-necked | | | |
| brave out | | | |
| brazen out | | | |
| bread and butter | | | |
| bread and circuses | | | |
| bread of life | | | |
| break a leg | | | |
| break a sweat | | | |
| break cover | | | |
| break down | | | |
| break even | | | |
| break gates | | | |
| break in | | | |
| break into | | | |
| break into a run | | | |
| break it to | | | |
| break one's back | | | |
| break one's chops | | | |
| break one's duck | | | |
| break one's lance | | | |