Top definition
An error screen featuring a sad cartoon cow in Zynga's FarmVille on Facebook, informing you that FarmVille is down yet again.
Prima: Hey, can you harvest my blackberries for me? I'm gonna be late.

Secunda: Sorry, it's been FailCow all night.

Prima: for FUCK'S sake.
by Einstein9073 November 18, 2009
Get the mug
Get a FailCow mug for your brother-in-law Manafort.