After having their 11th child, an Irish couple decided that was
enough, as they could not afford a larger bed. So the husband went to his
doctor and told him that he and his wife didn't want to have
anymore children.
The doctor told him there was a procedure called a vasectomy that
would fix the problem but it was expensive. A less costly alternative
was to go home, get a large firecracker, light it, put it in a beer can,
then hold the can up to his ear and count to 10.
The husband said to the doctor, "B'Jayzus, I may not be the
smartest guy in the world, but I don't see how putting a firework
in a beer can next to my ear is going to help me with my problem."
"Trust me, it will do the job", said the doctor.
So the man went home, lit a cracker and put it in a beer can. He
held the can up to his ear and began to count: "1, 2, 3, 4, 5,"
at which point he paused, placed the beer can between his legs so he
could continue counting on his other hand.
This procedure also works in New Zealand and Tasmania.