Brown Mystery 

When a person sharts himself or herself without knowing the shade, volume, or mass of the said poop. The only way to solve the mystery is to de-mask the villain, which by the way is your underwear. Try that on for size, Scooby Doo and friends.

Shaggy: "Zoinks Scoob, Like I just planted a double chocolate fudge surprise in my pants."
Scooby: "Ruhroh Shaggy, guess them Scooby Snacks were expired. Hehehehehehe."
Fred: "Well gang, looks like the Brown Mystery strikes again."

Brown Mystery by superbtoilet February 16, 2014

mysterious brown 

Mysterious brown: something brown on your skin or clothing that could be chocolate from a previously eaten snack or it could be dirt, or it could be shit. You can't be sure that it is chocolate or you could lick it off, so you have to clean it.

Oh no, I just ate a kit kat bar and then pet the dog and now I found something brown on my arm. That is some mysterious brown. I'd better wash it off with soap and water.

mysterious brown by DebbyHM December 9, 2018

Mysterious brown person 

Someone who has a very dark complexion but tells you they are from Swedish or German or something.

Hey is Mark hispanic?

No he's German. He's a mysterious brown person

Mysterious brown person by kay-hizzle May 14, 2007