Gaspar, the cat, is sitting at the window looking through the glass attentively. I join him trying to understand. I tap on the window glass to see if it triggers any movement outside. He looks at me and looks away. Nothing outside. I tap again and search in all directions. He looks at me annoyed and goes back to looking outside. I tap a third time on the glass. He stares at me. I scrutinize the terrace. Nothing. While I am preparing to tap a fourth time, he… bites me on the wrist. There! That should teach you not to disturb me with pointless, annoying and extremely distracting tapping. Geeez.