fair-haired boy

big boy

A large object or person.

blue-eyed boy

The favorite, especially a young one, especially of someone in power; a fair-haired boy (US), (Australian).

boy howdy

Expresses strong support or agreement.

boy in the boat

The human clitoris.

boy toy

A gigolo or younger man who is sexually pursued by an older person.

good boy

Well done, to a male.

mama's boy

A male who has a very close bond with his mother, and may consequently be perceived as soft or effeminate.

old boy network

A presumed unacknowledged system of association between childhood friends (especially those at school or university together), used for mutual assistance or favouritism.