A snipe hunt is one of a class of practical jokes that involve experienced people making fun of newcomers by giving them an impossible or imaginary task.

Inexperienced campers or hunters are told about a bird or animal called the snipe, as well as a (usually ridiculous) method of catching it - such as running around the woods carrying a bag, or making strange noises. Since the supposed snipe doesn't exist, the hunt never succeeds, no matter how foolishly the newcomer acts.

To extend the joke, there actually is a species of bird called a snipe. The success of the joke depends in part on the victim's ignorance of this, as the snipe is found primarily in wetlands and the joke is invariably played in wooded areas.

Another variation of this type of practical joke, called a fool's errand in the UK, involves sending newcomers on a work site to fetch nonexistent tools, such as a left-handed screwdriver, a can of striped paint or a tube of elbow grease.

In the Boy Scouts of America it is common for first-time attendees at a camporee (a large weekend event) to be sent after a "left-handed smoke-shifter," supposedly a branch with a fan on the end used to deflect smoke from a campfire. In the Air Force a variant involves new airmen being sent to the commissary to purchase a bottle of prop wash.

A traditional variation of this in UK schools involves a teacher sending a pupil—usually picked for being annoying as much as for gullibility—to another teacher for "a long stand". When the pupil arrives and delivers the request, they are asked to wait—usually in full view of the class: this is their "long stand".

In Latvia a similar hunt took place during Jani. Children traditionally went into the woods on Jani, searching for the fern blossom (like a "snipe hunt" in North America, since the fern blossom does not exist) which supposedly bloomed only at night on Jani. Searching for, and theoretically finding, the fern blossom brought good luck.

(info on Jani is here http://www.answerbag.com/a_view.php/6353 )