Scabs

Three men are outside a pub when one said, "I dare you to go in and ask for a free glass of milk!"
One of the other men went in the pub and said, "Can I have a free glass of milk?"
"Only if you pick the scabs of my daughter's fanny!"
replied the barmaid.
"Screw that!"
The other man walked in and said, "Can I have a free glass of milk?"
"Only if you pick the scabs off my daughter's fanny!"
replied the barmaid.
"Screw that!"
When the two men went back outside they told the third one that they could only get a free glass of milk if they picked the scabs off the barmaid's daughter's fanny.
The third man said, "I wouldn't mind doing that."
The third man went in and said I will pick the scabs off your daughter's fanny if you give me a free glass of milk."
"Ok," agreed the barmaid.
He went upstairs and picked the scabs of her daughter's fanny and put them in a crisp packet and sealed it up for freshness, then chucked it out the window.
He went outside to meet the others and told them that he got a free glass of milk.
The others said, "So...we got a free packet of crisps that flew from the sky!"