3D (n.) A word sometimes used in reference to the internet.
How "internet" became 3D:
First, some intellectuals said, "let's call the internet the
World Wide Web, because it sounds cooler and can be shortened to WWW." and the
World Wide Web and WWW was born.
Next, some people said "WWW (doubleyou doubleyou doubleyou) is too hard to say in normal
conversation, and Heaven forbid we should be reduced to using 'World Wide Web' 'cause acronyms are just cooler. Let's shorten it to dub-dub-dub which can stand for WWW" and Dub-Dub-Dub was born.
Once AOLers were introduced to dub-dub-dub, they said "dub-dub-dub takes too long to type out in IRC where we like to ruin our social lives in l33t style. Let's make it an acronym so that we can say things like 'WTF? u on teh DDD? omg, u r teh ROXORZ LOL!'" and DDD was born.
Then the n00bs said something to the effect of, "W7F? 73H UB3R DDD H45 N0 NUMB3R5 1N 17!!!11!!1 137S M4K3 17 3D 1N5734D!!1!1!!" and 3D was born.