The teacher asked the students to bring one electrical appliance for "Show & Tell," and the next day every kid had something.

The teacher asks Anna: What did you bring?

"I brought a Walkman."

"And what is it for?"

"You can listen to music with it!"

"That's nice. What did you bring Maria?"

"I brought a can opener, it opens cans!"

"Well done. Umm, Johnny, I see you didn't bring anything!"

"Yes, I did. It's in the hall."

So the entire class goes into the hallway.

"Umm, Johnny, what is that?"

"It's a heart / lung machine hospitals use to keep your heart going."

"Whoa. What did your father say about you bringing this?"

"He said, 'AAAARRRGGGH!!!'"