When given the choice between getting something of known value or something of unkown random value, the latter is denoted by the mystery box.

It might be fine to go for the mystery box. But human beings have a tendency to fall for the mystery box without weighing the outcomes first, seeking the thrill of gambling.
A boat is a boat, but the mystery box could be anything! It could even be a boat! And you know how much we want one of those. We'll take the box.

Who could resist the call of the mystery box.
by evilm0nkey June 14, 2017
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noun
pronunciation- "Mist-er-ee Box"

A game usually played by, or in the company of males. A cooler filled with a random assortment of beers, including all varieties ranging from the shittiest of beers to the better tasting beers. When one has created this wonderful device, you are to stick your hand in the cooler and grab the first beer that luck grants you. After a beer is pulled from the cooler, it is dishonorable and highly frowned upon to replace said "shitty beer" with one that is more to your liking. It is absolutley prohibited to place your hand within the cooler without first finishing the open beer at hand. If a player is to do this, elimination from the game, castration, and execution are all possible forms of punishment.

Rules are open to interpretation. For example, if a less manly male has decided to place a beverage that is usually shunned from the male society into the mystery box(i.e. smirnoff ices or Mike's hard lemonade), there can be a democratic vote to create a rule in which one would have to chug every "less than manly beverage" upon removal from the cooler.
Chuck- "Hey dude, come over to watch the playoffs. We're doing a mystery box. I just placed a six of redstripe and two 16oz budweisers in the cooler!".
Mark- "Right on! I'll bring over my remaining steel-reserve and smirnoff ices!".

Sean-"Hey bro bro, it's Ted's 13th Birthday, try to get some cervezas for him."
Carlos- "Sounds bueno, I'll raid my dad's fridge. He has Corona, Busch-Light in bottles, and Miller light. We can make a mystery box!!!"
by Red Stallion December 10, 2011
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This a motor vehicle used to take part in the Mystery box Rally.

The term arises from the fact that participants sign up to take part in the Mystery box rally without knowing what car they will be using or where they are going.
The cars are of unknown quality, and are usually secondhand cars that have been pulled out of the Manheim Auction System at random, and their value could be anywhere between $100 and $10,000.

The Mystery Box rally is a spin off of the Shitbox rally, and also raises money for the Cancer Council.
A mystery box is driven on a mystery route, to a mystery destination on the Mystery box rally
by Shitboxer September 13, 2013
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When you and your friends all cum inside of one girl and it’s a mystery of whose kid it is.
Nathan, Brennan, and Cole mystery boxed Patty last night.
by Trucknutz & n8air August 15, 2018
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When a girl is such a slut it's a mystery which std's she gon give yo ass
by BFC_Apples March 1, 2015
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Someone, who when playing Zombies on COD, who will do anything including fuck up the whole game for a shot at the mystery box.
by Mr. Callipygian September 23, 2011
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A man that is like a mystery box in that you wanna know about him until you find out about him and then say "why did i go with the mystery box?"
"Why did I choose Senior mystery box?"
"Because everyone wnats to know about the mystery box."
by Kapsule Corp. January 30, 2009
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