to fuck the shit out of somebody, then never talk to them again despite seeing them around a lot. Usualy occurs between upper and lower classmen in high school and college.
bro 1: jon derailed that chick at that party
bro 2: I know, shed in two of his classes to
Bro 1: awesome
by jon Appleseed July 30, 2008
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The act of throwing a thread in a discussion forum off topic, oftentimes so much so that the original discussion is unable to continue.

A common result of a troll attempting to have fun at the expense of people actually trying to use the forum.

A common result of a flame war between multiple users.

Commonly helped along unintentionally by people who are simply off topic, as well as the occasional Grammar Nazi
Here is an example as might happen in the forum of an unreleased video game:

Topic: Post your ideas for things you want the developers to put into the game!

Original Poster:
Hey guys Ill edit my post to add ur ideas to this post Ill start off with destructible terrain no one's pulled that off as well as X-Com did back in the day.

Grammar Nazi:
Man Original Poster! What's with all of the huge run on sentence! Use some punctuation while you are at it too. Also, don't say ur, abbreviations are for text messaging, no one's gonna take you seriously.

Troll:
Haaahaaa, whatever Grammar nazi, ur so shtupid, wher'd u get ur PHD, shtupid land? n` Original Poster, wat u doin playin such an old game like X-Com for, it's SOOOO dated, I hate da graphics and der are so many bugs n crap

Original Poster:
Hey, X-Com is still rated the #1 game of all time by a lot of people! Who cares if it's got dated graphics, and if you get the right version or a fan made patch you can run it on a modern system easy.

Moderator:
Troll, stop trying to derail threads, this is your first warning, two more and it's a ban.

And Grammar Nazi, don't correct people's grammar in a thread, if you absolutely MUST do it, send a private message instead so it doesn't clutter up the forum!

I see you two derailing a thread every time I log onto the forum. And Original Poster, get back on topic or I'm going to lock this thread,
by ZOMGRLY? February 24, 2009
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The name given to the condition when you cannot remember what the sprocket do-hickey is on a 10-speed bike that changes the gears.
I had three days of derailer syndrome until I went to the bike shop and asked the guys what the heck that thing was called that changed the gears on a 10-speed.
by TheRocketRod January 4, 2006
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An expression used to describe someone trying to fuck you in the ass, whether physically, personally or financially.
The car salesman was trying to sell me an air conditioned glove box, extended warranty and undercoating. I said hey buddy, "Stop trying to derail my corntrain"
by Matt September 1, 2004
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When family members are engaged in group sex with another family member and something happens (superficial or catastrophic) to bring it to an early or unexpected end.
We was all banging cousin Shirley out back at the family reunion when uncle Bubba's liquor still blew up and started an Alabama train derailment almost instantly.
by Gliterbob the Clown March 10, 2023
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A phrase, meaning to obstruct the flow of money.
some bitch: You ran your mouth to your parents, and now your living in a camper. You sure know how derail the gravy train.

some dude: I don't care if they own estates in Europe, the West Indies and America. I do miss my Ferrari Enzo, though.
by Cunty Fresh Fanatic November 12, 2010
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derail people are people, who study mechanical engineering at Karlsruher Institut für Technologie and are used to test the newest rollercoasters at Europa Park. In Fact they are just invited to die.
Are you one of those derail people?
You have to study mechanical engineering at KIT to become a derail people!
I was once a derail people - Markus Enger RIP 2019
by SadNiggaDerailer January 4, 2019
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