Piker

In more modern Internet parlance, a piker is someone who writes short and often seemingly irrelevant messages or posts on an internet forum or message board, generally for the sole purpose of increasing the individual's post count. This practice is largely frowned on by most moderators and message board communities.

Modern Australian slang. Someone who is invited to an event or outing, who confirms their forthcoming engagement but never actually attends. Also, one who attends an event but leaves early in proceedings.
ie."You're not piking already are you?"

Also: a shirker, avoiding doing ones fair share.

Piker also has several meanings with origins in St. Louis, MIssouri. In the 1904 World's Fair in St. Louis, the main amusement area was a wide street called the Pike. Students who hung out on the Pike that year were called Pikers. A newsletter about the fair was called The Piker. Several of the permanent buildings for the fair became the administrative buildings of Washington University in St. Louis. The football team for that school was called the Pikers, until the school voted for a new school mascot (the Bears). In 1985, Washington University's first a cappella group adopted the name the Pikers, from the school's previous mascot name.