That’s 1930s speak for “roller coaster.” At least it was to my grandmother, Gurnice Stephens. She grew up on Mt. Pleasant Orchard in Harford County, but worked as a nanny and a nightclub violinist in Baltimore during the 1930s and early 1940s. Perhaps she went to Glen Echo in Montgomery County and rode the “Coaster Dips” in the photo below. Perhaps more likely, her family frequented Atlantic City and Rehoboth Beach and the term might be from the seashore. She rode the Comet at Hershey Park not long after it was built in 1946. It’s probably the only roller coaster left at Hershey Park from when I was a child as well. Read up on roller coaster history here.