[waffle_ss]

I think the most realistic way to compress a tweet would be to replace words like "before" with "b4", "too"/"to" with "2", reduce whitespace (e.g. double spaces to single), and maybe start ripping out vowels ("vowels" -> "vwls").

Although not as efficient as demonstrated above, there are no external dependencies needed; the content can be decompressed by the reader's brain in-place at the slight cost of being difficult to immediately parse/understand.

[Jach]

There's also a social status cost, which could be great or small, for example if your readers have an intense dislike for netspeak and poor English.

[FuzzyDunlop]

Here in the UK it's interesting to note that, while text speak was all the rage a few years ago, it faded out.

It was replaceddddd by making wordssss actuallllllly longerrrrrr for no reeeeaaaasonnnnn!!!

Now the text speak is a bit more reined in and not totally incomprehensible like it used to get.

[hammock]

Actually making the words longer like that goes a long way to expressing emotion in your texts - while avoiding the use of emoticons, which make you look like a girl.

For example, adding letters to a word is especially useful when teasing someone- gives them a hint you're not 100% serious.

[andrewflnr]

I have observed that on occasion here in the US too.

[rorrr]

And how would you uncompress it?

B4 bs ws 2 lt.