Bum Scum derives from the Latin word of Bumus Scumus meaning Bum Scum. This may imply that you have not cleaned your rear end after pooping, or may also mean that you are one of the most fucked up people that I have ever fucking met.
I hope that guy falls of the stairs dies, he is such a bum scum
The lint that is in your ass crack that comes from your underwear!
Mike - "Man did u fuck that hot ass hoe last night?"
Ephraim - "FUCK NO THAT BITCH HAD TO MUCH BUM SCUM!!!"
A chewy toothpaste-green goo located between the buttcheeks around the anal opening. Possibly originated from swalling your chewing-gum.
I picked off a huge glob of bumscum. Let's go scare my mom with it.