A guy walking in the desert desperately needed a drink.  As he followed the dunes, he came upon another man riding a camel.  He asked the man if he had something to drink.

The man on the camel said "No, but if you like, I have a nice selection of ties.  Would you like to buy one?"

"No!" The first man replied.  "Are you crazy?  I need something to drink, not a tie!"

So the man on the camel rode on, and the walking man continued his slow and very thirsty trek for several days.  Finally he came upon a cantina.

He gratefully approached the doorman at the cantina and said, "I'm so glad I made it!  Can I get in and get some water?"

The doorman frowned at him.  "Not without a tie."