From The Collaborative International Dictionary of English v.0.48:
Pecker \Peck"er\ (p[e^]k"[~e]r), n.
1. One who, or that which, pecks; specif., a bird that pecks
holes in trees; a woodpecker.
[1913 Webster]
2. An instrument for pecking; a pick. --Garth.
[1913 Webster]
3. The penis; -- an obscene term for the male sexual organ.
[Vulgar]
Syn: penis, cock, prick, tool, peter, dick, shaft [all but
the first considered obscene].
[PJC]
Flower pecker. (Zool.) See under Flower.
[1913 Webster]