Bad Cafe Behaviors--Bad!

I promised in my last post that going forth into the world would soon yield someone, anyone, making you mad, and that would manifest as writing material.

Tonight I sat in a cafe and found three things that might spark a good scene, and by scene, I mean piece of fiction or a fight:

1. The man sitting behind me coughing at volume 11 with no predictability--spastic eruptions ruffling the back of my hair. I waited till he left for the restroom to change my seat. When he returned, he grabbed his things and left. Exquisite timing, sir. You're gone, yet no doubt your pathogens still coat the back of my head.
2. The mother who let her nine year-old child peer at me, uninterrupted, for a good minute. It didn't help the child observed me like someone trying to identify an alien life form. This same child then gave the adult a tour of a mathematical computer game. I wonder if they sell a Social Skills Game where folks help their children and themselves learn the expiration date on staring.
3. The barista impersonating a trumpet and breaking randomly into lyrics such as "the hills are alive with the sound of music." I'd need inspiration, too, clearing tables left cluttered with books patrons didn't have class enough to buy or return to shelves. I'd also want a good song to help me pass the time. But earbuds, man, and inner monologue; two AWESOME ideas. 

Insert misanthropic writer and you have your scene. But move the action out of my writerly head and get someone to take a stand, teach some manners, or belt out a competing song. Let things get dicey and way off track when someone does the unthinkable in a cafe. 

Finish the story for me. Pick your pet peeve of the three, or invent your own. Tell me what I ought to have done had I the wit, the insanity, or the gall to make a scene.