A sex position that involves a prone male partner who penetrates a (semi-)seated male or female partner facing 90° to his left or right. A more complicated variation known as a "Dutch Bicycle with Handlebars" involves an additional two partners facing the seated partner from the left and right, who the seated individual stimulates manually.
On the streets of Amsterdam couples regularly share bicycles, with one person riding "side-saddle" on a rear cargo rack. It is this common habit that gives name to the aforementioned copulatory posture.
To this author's knowledge the etymology of this bit of vernacular has no connection to the sex industry for which the Netherlands are renowned. However, contrary evidence--please include citations--is much appreciated!
"Did Michelle tell you she quit spinning class? She said she could never go back to a stationary after riding a Dutch bicycle."