The budget was always tight at the City Zoo, but there was always one perk to look forward to. Every December, the zoo administration doled out a small sum to each department of the zoo, to be spent however that department saw fit. It wasn't a huge amount, but it was enough to pick up whatever odds-and-ends the keepers felt that their section needed.
When the hoofstock department got their year-end reward, the head keeper summoned the newest member of his staff to his office in the giraffe barn. "I want you to take the money and go down to the thrift store on Elm Street. Buy us some duct tape, some zip ties, two new scrub brushes, and some coffee filters." At that moment, a fat fly - one of the hundreds that always filled the barn, attracted to the giraffes' manure - landed at the edge of the head keepers desk. With lightning speed, the head keeper smashed it into jelly with a tattered old flyswatter.
"Oh, will you look at that," muttered the head keeper, looking at the stained, tattered swatter, coated with years' worth of fly guts. "You better get a new flyswatter while you're out, too."
At the end of the day, the head keeper was at his desk, looking through some reports, when the new keeper entered. He held out a mug of coffee to his boss, who took it eagerly. They chatted briefly about the ins and outs of the day, what animals were doing what and so on. Finally, the keeper pulled a receipt from his pocket and put it on the desk.
"Well, I got the zip ties and the duct tape, and I got the scrub brushes and the flyswatter, but I couldn't find any coffee filters. Sorry about that."
"Oh? How'd you filter this coffee, then?" the head keeper asked, taking a sip. "I thought we ran out of filters a few days ago."
"Oh, easy. I just used the flyswatter."
"Oh, don't worry boss. I know what you're worried about and no, I didn't get your new flyswatter dirty by mixing coffee with it. I just used the old one instead."