Green’s Dictionary of Slang

pecker n.2

[SE pecker, that which pecks, i.e. a beak, a bill]

1. [mid-19C+] courage.

2. [late 19C+] (orig. US, also peck) the penis; a generic term for sex.

3. [1940s–80s] a general term of abuse.

4. [1980s] (US/Can.) a young child.

5. see peckerhead

In compounds

pecker check (n.)

[1980s] a health check, looking for symptoms of VD.

peckerhead (n.) (also pecker) [-head sfx (1)]

[1940s+] (US) an objectionable, aggressive person; also attrib.

pecker palace (n.)

[2000s] (US prison) a room set aside for conjugal visits.

pecker tracks (n.)

[1950s+] (US) semen left on a sheet or other similar object after intercourse or, usu., masturbation.

In phrases

keep one’s pecker up (v.) (also hold up one’s pecker) [sense 1 above; despite chronological impossibility, popular ety. usu. links phr. to sense 2 above]

[mid-19C+] to stay cheerful, despite possible adversity; often as imp. keep your pecker up!

stick one’s pecker in (v.)

[1990s+] (US) to interfere; to become involved.