The act of putting down toilet paper on the seat before taking a poo as the straight lines of toilet paper form the shape of an octagon. This is mostly done in public toilets or toilets alien to the user.
Pablo: Dude that's gross, those toilets are jank
Angus: Its cool, I octagoned the seat
Pablo: Even still, for me its my own throne or nothing
The art of octagoning is to tesselate the paper so as to block out all of the seat.