I can't stand it when people use anything short of their native language. Even though it is just an 'IM' it still pisses me off, looking through their message feeling like I'm reading another language, or decifering some kidn of code.
It's a lot more fluent and easier to read when its in proper english. It's not like it takes a lot of time to write 'you' instead of u. But I do say "lol" ocasionaly. Because it sounds more fitting, then when someone says somethign midly 'chuckle-worthy' and then say "haha" it just looks akward. But when they say lol it just accents the previous comment and all is well.
I used to say 'xD' and '
' a lot but I cut down a lot on that.