I can just about get
abbreviating "to" or "too" as "2".
But using "4" for "for" (sorry) really winds me up.
Say them out loud.
FOR.... FOUR....

Completely bloody different!

Add: And to make it worse, businesses use it when there is no NEED to abbreviate the word, Phones Four You? Gibberish.
(greatoldone Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl f'tagn, Fri 9 Apr 2010, 7:23, 5 replies)

Great
Some idiot at work writes "Wait 4 rest of job b4 sending on." on our job bags. I send the buggers on with a note on saying "Cannot understand gibberish note. Please write in English."
(Captain Spacker I lick windows, Fri 9 Apr 2010, 7:36, closed)

what are you on about?
for and four sound identical the way i say them ... are you saying four like "for-wer" or something?
(zenmeban thinks the weather could be better, Fri 9 Apr 2010, 9:21, closed)

no
"four" is similar to "fore".
"for" is a softer "o" ("faw")

I think the Yanks pronounce them both the same, though...
(greatoldone Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl f'tagn, Fri 9 Apr 2010, 9:53, closed)

I h8 that 2

(Vice Admiral Sir Charles Cockbrush KCB MBE DSO, who is finding it increasingly difficult to log into b3ta.com wants to duck your aunt and kick your puppy, Fri 9 Apr 2010, 9:22, closed)

I love the efficiency of Italian text-speak
"Ho tanto fame" ("I'm very hungry") becomes "80 fame" = "Ottanto fame". Brilliant.
( Pretender, Sun 11 Apr 2010, 19:50, closed)