When T-Rex finds someone to get vengeance on, it seems like he could use Urban Dictionary to do that. Then maybe try a Google-bombing. Better than thinking of an acronym, though, would be to turn their very name into something unpleasant. That seems like a much better way to get revenge on someone. If you do it right, then their name will live on for centuries, and people will use the word even when they don't know why it means what it means. For example, nearly anyone who uses "McCarthyism" as a word can tell you that it came from Senator McCarthy's hunt for communists in the '40s and '50s.
But the best example of naming something after your enemy is one you probably don't know of: the Molotov cocktail. During World War II, for plot-related reasons, the USSR went to war with Finland. The Soviets were dropping cluster bombs on Finland, but the their foreign minister* Vyacheslav Molotov completely denied this, saying that what they were really doing was delivering food to the starving Finns. The Finns started referring to the bombs as "Molotov bread baskets," and the Molotov cocktails they started throwing at tanks were "drink to go with the food."
Finland ended up losing the war, but they turned it into a war of attrition, and it lasted much longer than the Soviets hoped.** This is not exclusively because of the Molotov cocktail, but it certainly helped.
So if you have an enemy you want to get revenge on, don't just make up a dirty acronym with their initials. Any corporate tool can think of a backronym. Go the whole hog, and turn their very name into something awful.
And it's definitely a nerdy thing to say internet acronyms out loud when one is talking in meatspace. It's like, you're not even typing. What are you economizing on? It takes more time to say "double-you tee eff" than "what the fuck."
* - Technically, he was the "Commissar for Foreign Affairs" but that is pretty much the same thing.
** - Sound familiar? It sounds like war is governed by Hofstadter's Law: "It always takes longer than you expect, even when you take into account Hofstadter's Law."