Question: What is the most common computer password?
C) I Love You
Answer: Depends on who you ask ... because two former game show contestants are now suing the people behind "Million Dollar Money Drop" claiming they guessed correctly ... but were hosed out of the $580k prize.
TMZ obtained a lawsuit filed by Andrew and Patricia Murray ... who appeared on the Endemol-produced game show back in 2011.
In the suit, the Murrays claim they wagered $580k after receiving the question: "According to the data security firm IMPERVA, what is the most common computer password?"
The Murrays claim they guessed B, based on personal knowledge of surveys and articles and having read numerous studies on the Internet ... but they were told they were WRONG.
On the show, which aired on FOX, they were told the answer was A ... and the Murrays lost their shot at the money.
But in the suit, the Murrays claim they were tricked by Endemol producers ... because, "IMPERVA did not conduct its own objective survey of computer users but rather supports its assertion that 123456 is the most common password based on analysis of a hacking incident involving a website known as RockYou.com."
FYI -- the hacking incident referenced in the suit occurred back in 2009.
In the docs, the Murrays argue "If [they] would have known that the question was pertaining to a random, single incident ... they would have hedged their bets and played differently."
The Murrays argue that they were "tricked" -- despite the fact they were promised there would be no "trick questions." Now, they're suing Endemol, FOX, and others for the $580k -- plus punitive damages and other fees.