"Where is that screw?" 

"What screw? " Bob asked. 

"The screw I put on the counter to keep it safe till I needed it... that screw!" Dave responded with impatience. 

 "ohhh, that screw... I think we used it." 

"Really! "Where? Where did we use the one screw I had, that worked for that faucet fitting?" 

Bob looked up from under the sink, "Well, Boss, I don't know.... wasn't aware it was special!"

"Now I have to run back to town and get an assortment of tiny screws... hope'n one will fit!"

"Guess it's a real mystery, boss... yup...sure eniugh!"