While in the midst of wiping one's tush after defecating, the act of wiping, then folding the toilet tissue over to reuse it.
Brian: "Man, I was taking a dump in the school bathroom the other day...and it wasn't a very good one. I was wiping and wiping and wiping and still had to wipe more but I was running low on toilet paper."
Joe: "What'd you do....fold and reuse?"
Brian: "Uh YEAAAAAH.....did I have any other choice?!"