"The computer eventually tells them that humor is actually a psychological study tool imposed from without by extraterrestrials studying mankind. They needed to isolate the responses to their jokes from original ones, so they 'programmed' us to react differently to puns. They also find that figuring this fact out makes it useless as a tool, so the unidentified aliens turn off humour. Nothing is ever funny again."
Wee Billy from Glesga always wanted to look cool. His friend told him that he needed a good designer pair of trainers to go with his shell suit. Billy saved up all his Giros and all the money he got back from returning his empty bottles of Ginger and finally managed to get himself a pair of brilliant white trainers to go with his shell suit.
Proudly, he strutted down the street calling out to all the passers by "See ma new trainers? Stonkin, eh?"
One fine upstanding gentleman pointed out that they were indeed a fine pair of trainers but was young Billy aware that he had a lace undone? Billy scornfully retorted that it was part of being cool to have a trailing lace and that on the sole of the trainer there were instructions for the wearer to do such a thing.
When asked for proof of this instruction, Billy look off his trainer and held it upside down for the disbeliever to read.
Bloke goes in the shower one morning, his weekly belly-button-fluff removal completed, he feels in his navel, something hard. Gets mirror and light, looks in, sees head of a gold screw, wierd-shaped recess in the head. Pokes around, tries to get it out, no luck.
Off next day to a doctor who says he's never seen anything like it, but he can't get it out either. So on to a proctologist who says he's not qualified for that particular orifice, then a dermatologist who says it doesn't look dangerous, just leave it. Doctor after doctor says can't do anything about it.
Bloke is beginning to feel like a prevert, with this screw in his belly-button.
Despondent after several weeks of futile searching for an answer, he goes in a pub and has a drink. Sees old mate, to whom he tells his story. Mate doesn't laugh but suggest he tries the Wise Woman living on the hill. Poor bloke laughs it off, just goes home and sulks. But after a few such evenings he decides to try the Wise Woman.
(Cue for Black Adder joke if you like).
Anyway he turns up at the Wise Woman's house, she looks at the screw in his navel, hums and ha's, but says the only think she can think of is this: "sleep next full moon under an open window, drag your bed over to the right position, no bed clothes, just lie there."
Bloke pays her and goes home, thinks what a load of cobblers it all is, but come the bext full moon he drags his bed over under the window, opens this, pulls bedclothes down and waits. Moonbeam slowly moves around until it's shining on his navel: then he sees something !
A tiny but beautiful fairy is flying down the moonbeam towards him, a screwdriver under one arm. She lands on the bed, hops up to his navel, inserts the screwdriver - it fits ! - and turns..and turns..and turns...and slowly out comes the screw, about 8" long. When it's right out she nods her head, tucks the screw under one arm, the 'driver under the other, and flies back up the moonbeam.
Bloke feels so happy it's gone at last, he falls asleep with a smile on his face. Next morning he wakes up and feels - yes, the horrid screw is gone !
He jumps out of bed with a cry of joy, and his arse falls off.