A Japanese tourist got separated from his group on tour in Amsterdam. He ends up in the red light district, and decides to have a go. He enters a sex shop, goes up to the guy behind the counter and asks, "One condom please." He gets the answer they only sell condoms by six, nine or twelve. "But I only need one condom!" says the Japanese.
"Too bad, we only sell them by six, nine or twelve," is the answer from the shop owner.
The tourist really wants to know why, so the shop owner explains: "The package of six is for the Italians: Monday, Tuesday, Wednesday, Thursday, Friday and Saturday. Not on Sunday, as they have to go to church."
"Oh," says the Japanese, "So who is the package of nine for?"
"Easy, the French. Monday, Tuesday, Wednesday, Thursday, Friday, twice on Saturday and twice on Sunday."
The Japanese tourist is having the wildest imagination on the 12-condoms package, so he asks, "Who's that for?"
"Well," says the shop owner, "The package of twelve is for the English. January, February, March..."