Warm-up UEWV5ELV24 - this is a totally non-pornographic code. Experiment with xlate and see for yourself.
Hint it is really fast and simple, just open the page and try decoding with the various methods. You will recognize when you see it (not necessarily in the box you are expecting)

Warmup solution

It was really nothing: open xlate, start putting the data into the various fields and pushing decode. When trying with BASE32, it decodes to oS1ekXXX in the BASE64 box. XXX is porn, but this code is non-pornographic, so oS1ek remains, which is the Lost Planet 3 of the warmup train.

Main: +2189623809685983033395820256967 - this has nothing to do with xlate, so see description below.

Story There was a Morse-code puzzle a few weeks ago, which is a kind of variable-width code. However, besides dots and dashes, Morse-code heavily relies on the pauses, otherwise it becomes hard to interpret: .....-.-.-..----..-.-..-..--..-..- (no worries, this is just the code for "hard to interpret" without any breaks). Fixed-width encodings (like 2-digit hexadecimal or 8-digit binary representation of ASCII codes, both often appearing in puzzles) obviously do not have this problem, exactly because of their fixed length per codeword.

Puzzle There are variable-width encodings, which allow unambiguous decoding even without spaces. Depending on where you live, you may have to use one of them every time when you xyz. Where xyz is a quite common activity, people may do it several times a day, some may even seem doing it all the time.

Here is the code again: +2189623809685983033395820256967
It encodes a giveaway code in 12 letters (there is a number inside, simply written out, and upper/lowercase is denoted by U-s and L-s).

A bit more than a week. Games: some parts of a Capcom bundle, an obvious fake AAA giveaway, and one of the biggest AAA flops from this year, deluxe edition.

Hints

(Clarification hint: when you xyz in real life, you use a single code at a time)

Obscure pre-hint: this is not a Huffmann code, do not read too much about it...
Second part of obscure pre-hint: not much = read the first sentence only (English Wikipedia).
Third part of obscure hint: follow the links, and look for a short list in one of them. Keep the + in mind.
In short: this is a common type of prefix code, and definitely not a Huffmann code.

Revealing hint: the plus sign added (in front of the sequence)

Medium hint in my bump-chain.

When teachers wanted us to learn a lot of numbers (history lessons typically), we summarized the task as "learning the phonebook". Why would I write it here? I do not know.

Main solution

The puzzle was built around dialing prefix codes. While they have somewhat varied lenght (like +1 for North America, +36 for Hungary or +356 for Malta), they never start with each other. So they can be told apart without putting breaks into the sequence.
I used http://en.wikipedia.org/wiki/List_of_country_calling_codes, English names of the countries. The simplest way to look up was keeping a + in front of the numbers as you were typing into a find box.

jOG5Y is the giveaway code for the Lost Planet 3 of the main train.
The description explicitly said that there were 12 letters, so if someone found the 2-letter ISO country codes (24 "letters" in total), that should not cause too much problems either.

Warmup stats*

Pony stats*

* Data was updated in 8-12 hour periods for the last 3 days. It shows the final entry statistics now.