What is Z-cow?
An underachieving person, who by lack of intelligence or lack of motivation, simply believes anything a person says to be true, just because the person says it is true.
Jan is such a z-cow. She actually believed that Paris Hilton was running for president, because John said he saw it on MSNBC.
Anyone who believes something to be true if someone said it was on the internet.
Amy is such a z-cow, after seeing "parkalot" on Myspace she was determined to find the definition.