A: "I hung out with that cute blonde last night."
B: "Did you derail?"
A: "Hell yea. I derailed. So good."
by DryLee November 6, 2006
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
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
the act of sexual intercourse, usually referring to sex that is so hard it could knock a train off of the rail
Man, I derailed that chick so hard last night.
Would you care to join me for some derailing later tonight?
by Meeja July 18, 2017
Attacking or failing to follow the tactics of a debater who railroads the conversation, by expressing unexpected views or challenging logical fallacies.
She's upset because I took a third option that will derail her planned one-sided conversation.
by Poor Lurker August 2, 2012
To move from the pink, to the brown, when making the sweet sweet sechzor.

Or if you'd like it a bit clearer:

To go from vaginal to anal intercourse
Man A: Dude, I tried something new with my girl last night.
Man B: Oh yeah, what's that then?
Man A: Well, I went from pink to brown.
Man B: Oh...you derailed!! Fair play matey.
by Sid P June 13, 2007
A band from stockport/manchester
Arthur - lead guitar/lead vocals
Luca - rythm guitar/vocals
Will - drums
Sam - bass
IG @derailerofficial
Derailer are a great band
by will galliway January 26, 2018