from
http://www.word-detective.com/112700.html#piker
Dear Word Detective:
Having returned from a fishing trip where pike were not our sought-after fish, I wondered where the phrase "He is a real piker" came from. Any clues? -- Robert Levine, Old Greenwich, CT.
I'll give it a shot, but there doesn't seem to be a definitive answer to your question. The basic sense of "pike" as a noun is "something sharply pointed," especially a staff with a pointed end. The "pike" fish is so named because it possesses a long, pointed beak.
Untangling the history of "piker" takes a bit of doing. According to the Oxford English Dictionary (OED), a "piker" is "A cautious or timid gambler who makes only small bets; a person who takes no chances; a �poor sport� ... a shirker." A "piker," in short, is no fun at all.
There are a number of theories about the origin of "piker." The OED traces the word to the antiquated verb "to pike," meaning "to leave," which would certainly fit in with the sense of "cautious or timid." Originally, "to pike oneself" meant to obtain a pike or walking stick in preparation for leaving. "To pike" in this sense first appeared around 1420, and by 1889 "to pike" was being used in America to mean "to hold back or back out" in gambling.
Another possibility is that "piker" is rooted in the old British slang term "piker" meaning "tramp," from vagrants who traveled the "turnpikes," or toll roads. (The "pike" in "turnpike" was the barrier at toll booths which was "turned" to allow passage after payment of the toll.)
And yet another possibility, mentioned by Hugh Rawson in his book "Wicked Words," is that "piker" arose on the U.S. West Coast during the 1800s as a derogatory term for someone from Pike County, Missouri. Rawson points to "Okie," used in the 1930s as a derogatory term for migrants from Oklahoma, as a parallel to this possible origin of "piker."
If I had to pick one of the above theories, I'd go with the first, since "piker" in its modern sense seems to fit so well with the original "getting ready to leave" connotation.