I have a terrible cold, and I know exactly where I got it.

It wasn’t from that guy on the subway. You know the guy; he stands next to the door and gives a little…sniff… barely audible, nothing blatant like the guy in the seat there picking his nose. So subtle you don’t even think about it, until you’re beside him, ready to leave, and he sneezes all over you.

It wasn’t him.

It was from a kid at the clinic where I volunteer as a reader and wild-kid-wrangler.

I got it by being Entirely Too Clever.

Most of the kids come to the clinic for well-child physicals and immunizations. Yes, there are those who look feverish and exhausted, but they don’t come to me; they cling to their parents, who will soon look feverish and exhausted themselves.

Some kids who are otherwise healthy have colds. Colds don’t get no respect; if the kid’s scheduled to be weighed, measured and needled, mom brings him in, cold and all.

Who can blame her? Kids swap colds at school all week; why is a clinic any different?

As a former nurse, I take standard precautions to protect myself from tots with drippy noses. I wash my hands. I use hand-sanitizer. If somebody’s drawing in his snot with the blue crayon, blue does not return to my box.

But this four-year-old boy caught me up while I was being Entirely Too Clever.

He was bored. We’d read, drawn and colored, and the doctor still hadn’t called him. He squirmed and sniffled and wiped his nose on his sleeve. I felt sorry for him.

So I pulled out my iPhone.

You know those TV ads about iPhone aps? I have some dazzlers. What’s that song playing in the elevator? I’ll ask my Shazam. I’ve got an ap to flash LOSER, in three-inch neon-green running letters, at the Subway Sneezer as he pulls away from the platform. I’ve got a level tool with a bubble. Yelp. Facebook. Scrabble.

And I have Balloonanimal. Blow into the phone receiver; it inflates a picture of a long green balloon. Shake it; it twists into a dinosaur. Hit a pump icon, pump it up, up, up: Blam.

I showed the kid Balloonanimal.

No, I did not let him blow into my iPhone. I’m no idiot. I blew it up myself. Pumped it up. Popped it.

He jumped up and down. Do it again! I did. Do it again! I did.

The third time, he brought his face near the popping balloon and laughed, his mouth wide open.

Then he sneezed all over it.

There is no way to clean an iPhone with hand-sanitizer. And you can’t get them wet, so soap and water’s a no-no—except maybe to get rid of the streaks left on the glass by the hand-sanitizer.

I’ve got a horrible cold. But I’ve also got a learning curve. From now on, we stick to crayons and books.