A nail gun, nailgun or nailer is a type of tool used to drive nails into wood or some other kind of material. It is usually driven by electromagnetism, compressed air (pneumatic), highly flammable gases such as butane or propane, or, for powder-actuated tools, a small explosive charge. Nail guns have in many ways replaced hammers as tools of choice among builders.

Nail guns do not use individual fasteners. Instead, the fasteners are mounted in long strips (similar to a stick of staples) or collated in a paper or plastic carrier, depending on the design of the nailgun. Some full head nail guns, especially those used for pallet making and roofing, use long plastic or wire collated coils. Some strip nailers use a clipped head so the nails can be placed closer together, which facilitates less frequent reloading. Clip head nails are sometimes banned by state or local building codes. Full Round Head nails provide greater resistance to pull out as do ring shank nails. Nailers may also be of the 'coil' type where the fasteners come in either wire or plastic collation the advantage being a lot more fasteners per load, however, at the expense of extra weight. Industrial nailers designed for use against steel or concrete may have a self-loading action for the explosive caps, but most require nails to be loaded by hand. Nail guns vary in the length and gauge (thickness) of nails they can drive.

Nail may refer to:

A gun is a muzzle or breech-loaded projectile-firing weapon. There are various definitions depending on the nation and branch of service. A "gun" may be distinguished from other firearms in being a crew-served weapon such as a howitzer or mortar, as opposed to a small arm like a rifle or pistol, but there are exceptions, such as the U.S. Air Force's GUU5/P. At one time, land-based artillery tubes were called cannon and sea-based naval cannon were called guns. The term "gun" evolved into a generic term for any tube-launched projectile-firing weapon used by sailors, including boarding parties and marines.

In modern parlance, a gun is a projectile weapon using a hollow, tubular barrel with a closed end — the breech — as the means of directing the projectile (as well as other purposes, for example stabilizing the projectile's trajectory, aiming, as an expansion chamber for propellant, etc.), and firing in a generally flat trajectory.

The term "gun" has also taken on a more generic meaning, by which it has come to refer to any one of a number of trigger-initiated, hand-held, and hand-directed implements, especially with an extending bore, which thereby resemble the class of weapon in either form or concept. Examples of this usage include staple gun, nail gun, glue gun, grease gun. Occasionally, this tendency is ironically reversed, such as the case of the American M3 submachine gun which carries the nickname "Grease Gun".

Penn & Teller (Penn Jillette and Teller) are American illusionists and entertainers who have performed together since the late 1970s, and are known for their numerous stage and television shows. Their current Las Vegas show is an amalgam of illusion and comedy. Penn Jillette is a raconteur; Teller generally does not speak while performing, although his voice can occasionally be heard during their performance. They specialize in gory tricks, exposing frauds, and performing clever pranks. More recently they have become associated with atheism, scientific skepticism, and libertarianism, particularly through their television show Penn & Teller: Bullshit!.

Penn Jillette and Teller were introduced to one another by Weir Chrisimer, and they performed their first show together at the Minnesota Renaissance Festival on 19 August 1975. From the late 1970s through 1981, Penn, Teller, and Chrisimer performed as a trio called "The Asparagus Valley Cultural Society" which played in San Francisco at the Phoenix Theater. This act was sillier and less "edgy" than today's Penn & Teller act.^{[citation needed]} Chrisimer helped to develop some bits that continued, most notably Teller's "Shadows" trick, which involves a single red rose.