After having their eleventh child, an Irish couple decided that that was enough, as they couldn't afford a larger bed.
So, the husband went to his doctor and told him that he and his wife didn't want to have any more 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, and placed the beer can between his legs so he could continue counting on his other hand.