That's the "TP" in TP2000. There is a roll of standard-issue
toilet paper in each counterlung to act as a water trap.
While funny, this proved to be extremely effective, although
I later added a plastic reinforcing tube (pink hair rollers) to
the inside of each roll of TP to prevent collapse. Wonder if
you're leaking? Just squeeze the Charmin - if it's mushy,
you're taking on water. I did notice that cheaper brands
are actually better than the more expensive ones, because
the sandpaper-grade stuff tends to be rolled more tightly.