A sexual maneuver performed after girl-on-top copulation. Girl begins by sliding forward off of man's member, continuing up the stomach, chest and ending by sliding off man's face, leaving behind a trail of shiny, sticky, gooey ooze comprised of vaginal juices, semen, and any additional lubrication products used.
Bill: Hey girl, why don't slide up here and leave me a slug trail?
Tonya: Sure, give me a sec to dismount. That lube we used will make it extra-sticky!