There is no cow level

There is no cow level. Or is there?

As a saying
Blizzard has, for years, been denying allegations of hiding secret "cow levels" in their games, especially the original Diablo, where the rumors first began. (If you clicked a mysteriously-spawned cow several times, it supposedly opened a portal that led to a secret area, hence the name.) Descriptions vary from report to report of what exactly a "cow level" is, but they are generally accepted to be secret areas that contain significant numbers of bovines (sometimes including powerful, magic-wielding bovines) and little else. So prevalent were claims by fans to have found the "secret cow level" in any number of Blizzard's games that their repeated, pithy response became a common utterance for fans:

There is no cow level.

The fact that, taken out of context, this comment just sounds bizarre and practically invites one to look for a cow level because someone felt it was important enough to deny something so bizarre has probably contributed a large part to its spreading as a saying among fans. And it's just damn funny to blurt out.

Not helping rumors is the fact that there actually is a Cow Level in Diablo II, and there have also been numerous other cow jokes and "there is no cow level" jokes hidden in Blizzard's other games. For example, it was the cheat code in StarCraft used to skip the current level. The line lives on in the hearts of long-time Blizzard fans and as an occasional loading screen tip in World of Warcraft. In Warcraft III, players were able to access a secret level by locating a number of flaming sheep and killing them.

Curiously, the phrase bears resemblance to a famous quote in the movie The Matrix. When the protagonist of the movie, Neo, meets a young boy with telekinetic abilities bending a spoon with his mind, the boy explains "There is no spoon." This is also a cheat in Warcraft III. This phrase in turn has been interpreted as a reference to the Buddhist concept of dependent origination. There is no spoon: what exists is only Neo's idea of the spoon.

In the hit PC shooter games Call of Duty and Call of Duty 2, to enable cheats one must use the command console to set the value of the variable 'ThereIsACow' to 1337.

The Blizzard Entertainment-only band L80ETC has composed a Diablo-inspired song named "Raise Some Hell", which features the phrase "There's no cow level".

In Diablo III, there is another secret level that is very hard to get to, requiring multiple playthroughs, several rare items, a schematic, an ultra rare item that drops from an even more rare mob, and many more items. When all of the items are obtained, you must go to Tristram and find the cow from Diablo that exploded and it will resurrect into none other than the Cow King's ghost. After asking about the Cow level, he denies its existence with several bad cow puns and opens a portal to the secret level, Whimsyshire, the pony level, with aesthetics similar to My Little Pony.

During Diablo III's 3-year anniversary, May 15 to May 21 2015, the secret cow level was unleashed once again, with strange portals to the area opening.

Despite Blizzard's continued insistence that there is no cow level, it only seems to have increased the incidence of rumors, as seen below.

Tributes to the cow level in WoW
World of Warcraft contains several tributes and references to the cow level:
 * A BoE mace is named Wirt's Third Leg.
 * A BoE leather chest is named Cow King's Hide.
 * Mulgore, Thunder Bluff, and the entire tauren species can be interpreted as a tribute.
 * One of 's quotes in Gnomeregan was "There is no COW level... really! I repeat: there is no COW level.  Well, maybe there is..."
 * Diablo's 20th Anniversary