Green’s Dictionary of Slang

bazoo n.1

[Du. bazu(in), a trumpet]
(US)

1. [late 19C+] mouth; thus talk.

2. [1910s] an orator.

3. [1980s] (US) the vagina.

In phrases

blow (off) one’s bazoo (v.)

[late 19C–1940s] (US) to boast.