Butt Flag 

That annoying bit of toilet paper that sticks to your ass and waves like a flag after you get off a public toilet that you have lined with toilet paper to keep your ass clean and free of ass cooties. It can also be formed when you wipe your asshole with toilet paper and then it unfurls in your fingers; one end remains stuck to your asshole while the other end dangles freely from your hand.

I had to shit in the outhouse and lined the toilet with TP so I wouldn't pick up ass cooties. When I finished and stood up, I sported a really annoying butt flag that was hard to remove. One time I even wore one home and didn't know it until I removed my underwear; fortunately, my wife didn't notice it.

Butt Flag by Nickelman shits. August 25, 2011

butt flagging 

A golfing act, where one mate picks up the golf flag and throws it so hard it gets entrenched inside his friends ass hole

I cant believe my mom took me to go butt flagging for my birthday. My hole still hurts!

butt flagging by Dickfiddler April 8, 2017