"The metronome affair" joke

I had purchased a talking metronome while I was attending a conference in New York for music teachers. Before my son and I boarded our flight home, I hefted my carry-on bag onto the security- check conveyor belt. The guard's eyes widened as he watched the monitor. He asked what I had in the bag, then slowly pulled out the six-by-three-inch black box covered with dials and switches. Other travelers, sensing trouble, vacated the area.

"A metronome," I replied weakly, as my son cringed in embarrassment.

"It's a talking metronome," I insisted. "Look, I'll show you."

I took the box and flipped a switch, realizing that I had no idea how it worked...

"One... two... three... four," it said, after a while.

Everyone breathed a sigh of relief.

As we gathered our belongings, my son whispered, "Aren't you glad it didn't go' four... three... two... one...?'"