Guitar

The Electric Guitar is a close combat weapon introduced in Left 4 Dead 2.

Like all melee weapons, the Guitar takes the place of the Pistol slot. It can decapitate Common Infected. Each time it kills a Common Infected, it also gets blood splattered all over it. The Guitar appears to be based on an Ibanez GAX70, and when it makes contact with a physical object, it makes a random strum noise.

The Guitar does friendly fire damage to other Survivors, and can also instantly kill or severely injure Special Infected. However, most Special Infected either have destructive effects when hit or aren't worth the trouble of getting so close, so you're usually better off shooting them.

Trivia

 * In the first footage, the electric guitar did not have any visible strings, but if it hits an Infected, it would make a strum sound. This has now been fixed as new videos and the demo show it to have three remaining strings. It also sounds as if it were plugged-in, however it's obviously not.
 * The Electric Guitar could be a tip of the hat to Electric Guitars used in the video game Dead Rising, as if either guitar makes contact with a zombie, it sounds as if it as been hit while it was plugged into an amp. A few of the slammed chords sound identical.
 * The Guitar is a unique weapon of Dark Carnival and The Parish campaigns. It cannot be found anywhere else, and is extremely common in these campaigns.
 * Occasionally Ellis will refer to this weapon as an axe, referencing how many rock artists refer to their guitars as "axes".
 * The finale of Dark Carnival has a lot of Electric Guitars for the Survivors to use since they're on a stage where the Midnight Riders were going to play.
 * Like the Katana and Frying Pan, the Guitar has been viewed as a somewhat unorthodox weapon for a zombie outbreak. However, it was probably added to set a mood that Louisiana was abandoned during one of the many festivals that take place in New Orleans. Altough it may be that in The Parish campaign someone had an electric guitar before the infection and some people may have brought it with them for entertainment in the safe rooms