I was about to say the same thing. I’m not sure if I’ve ever seen it spelled “trank”, and if I had, I wouldn’t immediately know what it meant except in context ,as opposed to “perk” vs “perq”, both of which are immediately obvious (albeit with multiple possible meanings for the former.)
No, there can’t be a shortened version of something that itself is not a word.
Wow. How did I do that? I’m slipping. Nuclear.
This is the same phenomenon that changed “mike” (short for “microphone”) to “mic,” which always sounds like “mick” in my head.
Personally, I favor perq[sup]u[/sup], but I’m weird that way.
Well, neither dictionary.com nor m-w.com have a listing for it. My OS X dictionary finds “tranq” under the main definition “trank” listing it as “(also tranq)”.
That said, “tranq shot” does indeed return a hell of a lot more (>10x) results than “trank shot.”
ETA: However, “animal trank” returns about 5K, and “animal tranq” about 4K.
Just perchè.
Butter.
Perk. I didn’t even know of the existence of the word perquisite. And knowing that word is the only reason you’d allow such a nonstandard spelling as having a q at the end of a word, without a ue. (Iraq excluded because it’s foreign.) That’s why tranq still exists–everyone knows it means tranquilizer.
Not quite, but close enough. I always assumed the derivation was similar. I seriously just learned of the existence of perquisite in the last couple of weeks. And I’m someone who always maxes out on those quizzes that test your vocabulary. (It was actually one of the things that my psychiatrist used to discover I had OCD.)
And now it’s on a message board where someone else might discover it. 
I’m thinking that there’s a generational distinction here between the people who didn’t know perquisite was even a word and those who do. As we’ve seen here, lots of people know the word, perk (the reasonable way to spell it), and don’t even know it’s derivation. That’s because the word, perquisite, is no longer in common use, but perk is. But if you’re old enough, and god knows many of us are, you will recognize the word on a vocabulary test. That’s also probably true for lots of words. (Hijacking my own thread - many years ago I had to take the GRE. I had been out of school for quite some time. Results showed I killed the written portion, but didn’t do as well in the math. What I remember about the math was that it had several questions of a type that I had NEVER seen before, and so struggled with to solve by my old-fashioned ways. I figured that younger people taking the test would be familiar with those types of questions and would do better on them, having learned some easier or quicker ways of figuring them out, but I was plenty well-groomed in grammar and language use, as opposed to many of the “kids” taking the test, who had gone through school when those things received less emphasis.)
The word is spelled “perk.” There is no English word “perq.”
Something else I discovered by looking this up is that apparently in Australia “perk up” means “to vomit”. Does it also have the “cheer or liven up” meaning in addition?
I haven’t heard it used here for vomit, but I have heard it used for “cheer up” and someone who is “perky” is in good spirits. I wonder if the vomit use is out dated, or restricted to a particular population.
As long as we’re at it, the word *perk *existed long before coffee percolators but once it came to be used as a short form of percolate, it became confused with the original meaning, polluting the meaning of percolate. *Percolate *means filter gradually, not “violently toss something up and make a popping noise.” 
Landscapers speak of a *perk test *meaning to measure at what rate water is absorbed and filters through the soil (although they may spell it perc).
Anyone know where the OED stands on this highly contraversial issue?
Its literal meaning in Latin is ‘go through a colander’ (or sieve, or or strainer, or filter). Per- means ‘go all the way through to the other side’. Colum means ‘colander’ (or sieve/strainer/filter).
I blame Bush.
[sup]I can’t believe no one beat me to that… You’re slipping, people. Especially you Lefties. No more perks for you![/sup]
Lefties don’t perk their coffee anyway - they use drip coffeemakers.
Nuclear physics ain’t so new, and it ain’t so clear!
IIRC Carter also said nucular. It shouldn’t have been used as evidence of Bush’s lack of intelligence. It was only approriate in parody as a mannerism.
Also, going back about 20 years, my 5 year old wanted to get nuclear Pepsi. It was actually the short lived Clear Pepsi, which was new.