Just put it on my bill

A man ran into the house breathless and he said to his wife, ‘Honey, you should be so proud of me, I just saved $1.50 by not taking the bus, but I chased it all the way home. The wife replied, ‘You want a medal for that? You should have chased a cab and saved yourself 15!

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A duck walks into a pharmacy. He says, ‘I’d like a chopstick.’ The pharmacist hands him the chopstick and asks, ‘will that be cash or charge?’ The duck replies, ‘just put it on my bill.’

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A biology student had to write a computer program, but he had troubles to make it work. He asked his roommate, who was a computer science major, to look at his program and tell him where the error is. The computer guy looked through the code for some time, then glanced desperately at his friend and said: ‘In DNA’.