One day an Irishman goes into a pharmacy shop, reaches into his pocket and takes out a small bottle and a teaspoon. He pours some liquid onto the teaspoon and offers it to the chemist. "Could you taste this for me, please?"
The chemist takes the teaspoon, puts it in his mouth, swills the liquid around and swallows it. It tasted unpleasant. "Does that taste sweet to you?" says Paddy.
"No, not at all," says the chemist, pulling a face.
"Oh that's a relief," says Paddy.
"The doctor told me to come here and get my urine tested for sugar."