Zombicidal

Someone on the official forums found a very special Infected while browsing the population.txt file: common_male_jimmy, otherwise known as the Infected version of Jimmy Gibbs, Jr, the famous Super Cup racecar driver from Dead Center!

The Infected model, which has no known placement naturally in the game, has a thousand health, no gibs, has an attack similar to a Mud Man (in that his hits splash the screen with mud), and he can be killed in a single swipe from a melee weapon. He also has a set of unique dialogue reactions from the Survivors, including:

• “Sorry about this Mr. Gibbs, but we need your car.” ~ Coach
• “HEY! Jimmy Gibbs!” ~ Coach
• “HEEEEEEEEEEEEEEELLLLLLLLLLLPPPPPPP!” ~Ellis
• “Dibs on Gibbs.” ~ Rochelle
• “God damn that Jimmy Gibbs Jr.!” ~Nick

To spawn him yourself, use these commands:

map <mapname>
sv_cheats 1
z_forcezombiemodelname common_male_jimmy
z_forcezombiemodel 1
z_spawn

EDIT: Jimmy spawns randomly in the finale of Dead Center, it seems! I was playing in Expert difficulty a couple nights ago, and he spawned a few times. Usually, he spawned near the bathrooms at the start, but he may also spawn randomly during the event. Here are some screenshots:

Elunah Left 4 Dead 2 console, Infected, jimmy gibbs