If the term Mail it in originated from the movie, Van Wilder. It has evolved to be used more so in sports now. When a team actually has a chance or shot to win or contend, and they don't even put forth their best effort. Or perhaps settling for par in a quarter to save someone for later in the game or in 1 game in a series of games, or in a playoff stretch. When a team or manager doesn't believe they have a chance, but the fans or players actually do, and a critical decision is made that pretty much lets everybody know.
Fan,"They are only 4 games out with 2 weeks left, and Griffey isn't even the lineup, I can't believe they mailed it in".(the season) Fan,"bottom of the 9th, up 1 run, and you don't bring in the stud closer because you used him last night,they are mailing it in". "The manager is goin to mail it in".
by brian kessel September 20, 2006
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Mail is a slang sometimes said softly during anal sex by heterosexuals or homosexuals. It is said right before the penis is inserted into the other person's anus.
Note: It is never shouted or written with an "!" because during so might scare the receiever or cause them to scrim and could cause anal rupture.
Proper way
A: "Hey there. Mail."
B: "Uhhwhwhhhh. Yessssssssss."

Not the proper way
A: "....MAIL!"
B: "AHHHHHHHCH!!! MY ANUS!!!"
by Jim Blyth November 12, 2007
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It is equal to e-mail or email or electronic mail.
- Hey, John, can you tell me your @mail, please?
- Of course, Dick. You can write me to *******.*******.**
by Axellis March 21, 2007
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To call out a co-worker for being lazy as it there last day.
"Tim you have really been mailing it in today, how about you actually get something done"
by Jahney November 2, 2007
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A rare form of naked mole-rat only found in awkward situations in the cafeteria.
While talking to the guy she liked, a Maile appeared. :)
by UnstoppableAwkward151 January 15, 2011
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Mail me my money, man!
They wanna take my mail!
by Jake November 23, 2003
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Friend_1: *something funny*
Friend_2: "MAIL! "
by Schroedinbug January 26, 2019
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