I must present the joke first, with no lead.  I have shamelessly ripped it off from email, so some readers may have seen the joke.  Plunging ahead anyway ----

Hans, a middle-aged German tourist on his first visit to Orlando, Florida, finds the red light district and enters a large brothel. The madam asks him to be seated and sends over a young lady to entertain him.

They sit and talk, frolic a little, giggle a bit, drink a bit, and she sits on his lap. He whispers in her ear and she gasps and runs away! Seeing this, the madam sends over a more experienced lady to entertain the gentleman.

They sit and talk, frolic a little, giggle a bit, drink a bit, and she sits on his lap. He whispers in her ear, and she too screams, "No!" and walks quickly away.

The madam is surprised that this ordinary looking man has asked for something so outrageous that her two girls will have nothing to do with him. She decides that only her most experienced lady, Lola, will do. Lola has never said no, and it's not likely anything would surprise her. So the madam sends her over to Hans. They sit and talk, frolic a little, giggle a bit, drink a bit, and she sits on his lap. He whispers in her ear and she screams, "NO WAY, BUDDY!" and smacks him as hard as she can and leaves.

Madam is by now absolutely intrigued, having seen nothing like this in all her years of operating a brothel. She hasn't done the bedroom work herself for a long time, but she's sure she has said yes to everything a man could possibly ask for. She just has to find out what this man wants that has made her girls so angry. Besides she sees a chance to teach her employees a lesson.

So she goes over to Hans and says that she's the best in the house and is available. She sits and talks with him. They frolic, giggle, drink and then she sits in his lap.

Hans leans forwards and whispers in her ear, "Can I pay in Euros?"

The Lesson?

This is like the magazine cover indicator or the taxi driver/shoeshine boy with stock tips.

When something hits the mainstream media, the trade is crowded.

This joke is too long for Jay Leno, but the concept is clear.  I hope you enjoyed a chuckle.

Meanwhile, the ads on financial TV are shifting from selling gold to selling currencies.  This might be a warning that there is a crowded trade out there......