If I had taken the time to do that, I would have seen that the lid then read, "CLOSED." Now this may seem obvious to you, but think about it--the word "OPEN," followed by an arrow, could mean that the lid is currently open OR it could mean that you should twist the knob in the direction of the arrow to open the lid. See?

Now, as I've said, had I simply twisted the knob I would have gotten my answer soon enough. However, I chose the even quicker route of tipping the mug over to see if any of the scalding hot tea would spill out. On my hand.

And so we learn that instant gratification is not always good for us, that sometimes it actually hurts a lot, and that it may cause people in Starbucks to give you dirty looks.