Is it normal to intentionally piss on a bathroom mat at a house party?

Sometimes I go to house parties where I only know a couple people. Every once in awhile a bathroom at the house party has one of those fluffy bathroom/toilet mats that fits around the toilet. Sometimes if I am bored I will intentionally piss on the mat a bit. I usually try to piss on the back of it so that it is not immediately obvious that the mat is soaked with urine. This is easiest to do if the mat has a dark color, as it won't be as obvious that it is wet. Those bathrooms must reek of the smell of piss the next day and nobody has ever figured out that I have done this at any of these parties.

As far as I know, the people hosting the parties probably assume that any piss on the mat ended up there on accident!