It's the layer of toilet paper you place to cover your shit when the toilet doesn't flush. It's a kind-hearted gesture to save the person who next goes into that cubicle the indignity of seeing your motherload.
Wesley: Whoa!!! I feel sorry for whoever goes in to that bathroom... The toilet wasn't flushing.
Kirsty: Oh man... Did you at least leave them a helipad?
A "helipad" is when one feels an allmighty crap coming and places a rolled up peice of toilet paper in the water to act as a floatation device prior to releasing the "demon within" to eliminate the effects of "splashback"
after a big night on taco bill's "owwww i dont feel so good.....im going to have to lay a helipad for this bad boy"