When you have to return the bathroom, some time after taking a shit and initially wiping, to wipe again. This could be due to a number of different reasons like; not wiping properly the first time, anal leakage, swampass, ect.
If you asshole itches this may be a sign that you have to double wipe. May be referred to as DW for short.
Man, I think I need to go double wipe, my asshole itches.