Tentacles or GTFO!
Tentacles or GTFO! is a common phrase used in IRC for when a person desperately needs a fap, and the normal "Tits or GTFO!" doesn't help. If a person is unable to immediately provide a link to an image of tentacle porn within thirty seconds, they are immediately banned by the chanop who called it. This, along with the fact that most people don't know where to look for tentacle porn, accounts for the low population of #asciipron on Freenode. This sudden bannination and its effects are collectively known as The Tentacles or GTFO! Theory. Tentacles or GTFO! is generally declared porn emergency 4, in that one wants weird pornography but not so much so that they resort to porn emergency 5.
The phrase "Tentacles or GTFO!" is derived from three phrases. "Tentacles" denotes that the user wants to see tentacles, but also implies that they want to see said tentacles inside something they don't fit in. A picture of Cthulhu isn't enough- Cthulhu has to be making a mortal suffer in unspeakable ways. "Or" implies a threat, while "GTFO" is the actual threat- failure to comply can result in you getting kicked, banned, or sodomized with tentacles (plural). The Internet is indeed serious business.
This section is not, in fact, meant as padding so that the writer doesn't have to see the disgusting tentacle porn image below while previewing this page.
If, like the ten thousand people who have seen the picture to the right and immediately had to clean out your pants, you have suddenly realized the reason behind the "Tentacles or GTFO!" craze that has been sweeping the Internet, you need not read the rest of this section. If, however, you belong to the 0.005% of this article's reader base that didn't experience a massive erection (or you happen to be female), read on. (it wasnt a MASSIVE erection, can i still read on?)
The answer is simple. Anime characters being penetrated in all sorts of Kama Sutra-esque ways by inhumanly large tentacles sprouting from nowhere in particular is HOT. Why, exactly, this is is something that the psychology community has yet to piece together a reasonable explanation for. Its extreme improbability is a mystery that nobody has cracked yet. Maybe it has something to do with Rule 34.
The example on the left shows the real-life science fiction substitute for tentacles. Usually these involve some sort of weird creature with tentacle like tendrils overwhelming the subject. Usually this is not done in a sexual manner, but if the image on the right is considered too grotesque to use or the subject who wants the imagery is in a work-related environment, science fiction provides an excellent substitute.
What to do when asked
Something to keep in mind at all times when someone tells you "Tentacles or GTFO" is that they have been driven stark raving mad by the idea of tentacle porn. YOU MUST send them a link to tentacle porn immediately if this happens! If the above image doesn't placate them, you may have to glue foam tentacles (what do you mean, you don't have any spares lying around? Creep.) to your ass and take a picture- or, even worse, browse Encyclopedia Dramatica for pictures. If all else fails, you can even try 4chan, though you can't blame us if you leave the site in a different mental state than when you entered it.