A Coaster Step is term used in swing dances, in particular in West Coast Swing to describe a Triple Step done in the pattern "back-together-forward" or "forward-together-back". Most often it is the follower's step. As of 1994, the Coaster Step was still used in "Ballroom Swing", and is an identifying feature of that dance. This step may be used in more complex step patterns, e.g., in one of Whip patterns.
Coaster Step used instead of Anchor Step
Early in the 1950s, when "West Coast Swing" was known as "Western Swing", the Long Beach Arthur Murray Studio had a staff of top swing contestants, including Karma Halton, one of the top female dancers among them. At the end of a pattern, she "Coasted", turning her body on an angle as she swiveled back left and forward right before walking back toward her partner.
The Bronze Level syllabus for Western Swing included in the Dance Book written in the 1950s by Arthur Murray Dance Studios National Director, and Los Angeles basin resident, Laurï¿½ Haile, defined a "Coaster Step" as cross forward place, or back together side, or back forward back. Her written description of the step(s) does not include any swiveling. However, Her written description variations of the second triple of the "Basic Throwout" includes the following, "On the 2nd 1-2-3 the girl can take a sharp turn LEFT... Her styling here is to be on the balls of both feet, with both knees bent and pointing to her LEFT."
Although Haile used the term "Twinkle" to refer to a "back-together-forward" triple step, the 1971 edition of the "Encyclopedia of Social Dance" defined "Coaster Step" as "back-together-forward" in its description of "Western Swing".
Pulled from: http://en.wikipedia.org/wiki/Coaster_Step