A strange phenomenon which occurs when you are watching porn with your girl on a leather couch. As she begins to get wet with excitement (at this point she is probally naked or bottomless) she will leave a sticky streak of lube from her vagina as she moves across the couch, resembling a trail of slime left by snails and slugs
Deb got so turned on by the lesbo video she left a snail trail across my new couch.
A Snail Trail is when a female leaves a sticky residue in their underwear or when they leave a slimy trail on a surface such as furniture, a bed, or on a chair. It will sometimes appear as a moist, damp, or a wet spot but will often resemble a trail that a snail will leave behind, usually requiring Lysol or Clorox (both recommended) to clean up. It can appear as a fluorescent white, sticky, glue like substance that will harden if not cleaned up immediately, but will sometimes contain blood making Clorox absolutely necessary. If the Snail Trail is brown, it can indicate the individual doesn't wipe their ass or they have a turtle head peaking out. It may or may not have a smell, depending on the size and the color of the trail.
That girl I had over last night left an epic snail trail all over my bed sheets and my pillow case. What the fuck was she doing, riding my pillow? I had to use a whole can of Lysol to clean that shit!