In 1999, the movie Office Space came out, and since then, everyone has been pretty familiar with the term "O-face." Certainly your mattress is familiar. But while the O-face is the expression you make during an intimate moment of vulnerability/when you have a few minutes free in a 7-Eleven bathroom, I would opine that there is another intimate, oft-unseen face we all have, and unlike the O-face, we want to share this with no other humans at all. Yes, the toilet face.
I am no statistician. I'm not a researcher, I have no lab, I don't conduct studies for a major university. I am basing this entry on nothing more than a strong hunch. My hunch is that, maybe often, maybe only once in your entire life, you had a difficult time going to the bathroom. And as you attempted to exorcise that uncooperative turd with the power of will, the power of Christ, the power of deep breathing and panic, your face contorted into a mask of deeply contemplative terror and anguish. Like those unflattering images of Beyonce's performance at the Super Bowl, so too did you screw up your facial muscles and bear down to give it your all. And rather than a quick Destiny's Child reunion, you gave unto your tiny room a few muttered curse words and maybe a groan like a great bear settling in for the night. And the expression on your face can best be described as "what you look like while trying to s**t."