This shaggy, shaggy tale was posted on the groaners listserv. Be thee warned.

One Monday, a man goes into a pub for lunch. He orders his lunch and a pint from the barman, and takes a seat.

He’s never been there before, and is therefore quite surprised when, all of a sudden, a spider runs out of the kitchen, across the floor, up the side of the bar, across the bar, down the other side of the bar, across the floor, up the wall and out of the window.

About an hour later, the spider comes in the window, down the wall, across the floor, up the side of the bar, across the bar, down the other side of the bar, across the floor and into the kitchen.

He’s so amazed by this spider, that he goes to the pub for lunch on Tuesday as well.

He orders his lunch and a pint from the barman, and as he’s sitting there, the spider runs out of the kitchen, across the floor, up the side of the bar, across the bar, down the other side of the bar, across the floor, up the wall and out of the window.

About an hour later, the spider comes in the window, down the wall, across the floor, up the side of the bar, across the bar, down the other side of the bar, across the floor and into the kitchen.

He tells a friend about this, and so on Wednesday they go to the pub together.

They order lunch and a couple of pints from the barman, and sit down. After a little while, the spider runs out of the kitchen, across the floor, up the side of the bar, across the bar, down the other side of the bar, across the floor, up the wall and out of the window.

About an hour later, the spider comes in the window, down the wall, across the floor, up the side of the bar, across the bar, down the other side of the bar, across the floor and into the kitchen.

His friend is astonished by this, too, and so the next day they both tell a couple of people about this, so come lunchtime, there are about six or seven people in the pub, ordering lunch.

As they wait, the spider runs out of the kitchen, across the floor, up the side of the bar, across the bar, down the other side of the bar, across the floor, up the wall and out of the window.

About an hour later, the spider comes in the window, down the wall, across the floor, up the side of the bar, across the bar, down the other side of the bar, across the floor and into the kitchen.

Everyone is astonished by the behaviour of this spider, and so on Friday there is a huge crowd of people filling this pub at lunchtime, waiting for the spider.

Sure enough, eventually the spider comes out of the kitchen, across the floor, up the side of the bar, across the bar, down the other side of the bar, across the floor, and up the wall. It then runs back down the wall, across the floor, up the side of the bar, across the bar, down the other side of the bar, across the floor and into the kitchen.

Our hero is confused by this, and asks the barman, “Why, on Monday, Tuesday, Wednesday and Thursday did the spider run out of the kitchen, across the floor, up the side of the bar, across the bar, down the other side of the bar, across the floor, up the wall and out of the window, and then about an hour later, come in the window, down the wall, across the floor, up the side of the bar, across the bar, down the other side of the bar, across the floor and into the kitchen, but today it came out of the kitchen, across the floor, up the side of the bar, across the bar, down the other side of the bar, across the floor, and up the wall, back down the wall, across the floor, up the side of the bar, across the bar, down the other side of the bar, across the floor and into the kitchen again?”

And the barman replies, “Because the window’s closed.”