Derail; a verb. Used to indicate the exact point of derailment, AKA EPDI (Exact Point of Derailment Indication) A topic is derailed when someone clearly goes off-topic with posts which are obviously not associated with the original topic subject, or goes about anally raping the topic tavles by posting huge-ass pictures.
Let's derail that fucking topic!

That topic is bound to derail.
by MeMB January 4, 2005
one who gets plowed like a piece of land; one who gets laid the fuck out, one who gets bombed by sharif
Holy shit dunne just got derailed and broke his wrist.

WOW, Pauly Tess just got derailed.

HOTDIGGITYDOG, Stup just got lined up and defuckinrailed.

Wilferd Brimley here, If you or someone you know has dyabeetus and got derailed call Liberty Medical now.

by Wilferd April 23, 2010
To beat another person or group of people in a competition.
by FusionBolt2 April 15, 2011
This is when you mistakenly fallout of the vagina and literally smash the sphincter or asshole of a woman during sex.
I was having some intense sex with this chick, but I derailed and ruined everything. Especially her asshole.
by namgorf January 21, 2009
(on a newsgroup or messageboard) one who changes the topic of the thread, hence "derailing" it.
Jim is such a derailer, I just want to talk about shoes, but he keeps trying to cyber my anus.
by Jim March 25, 2003
E-mailing while inebriated.
I downed a half pint of scotch and spent the rest of the night derailing old girlfriends.
by Folook November 27, 2007
DERAIL; a term used by the shmoo clan in order to replace shit, do it, and pwn.
1) Dude i have been holding this in but i really gotta deRail!!
2) Are you ready? Lets deRail!!
3) Dude you just got DERAILED!
by Nathan C. August 26, 2005