The brown stains left on sheets, clothing, the floor of the shower, etc. from your spray-on tan when you are wet or sweaty. The most embarrassing tell-tale sign that you've been to the spray tanning booth instead of outside in the natural sunlight.
He told me he was so tan from all of his outdoor activities, but when he spent the night he left tanarrhea all over my sheets from his spray on tan!
OMG, I was rubbing my leg against him while we were dancing and suddenly realized I'd left tanarrhea all over his jeans!