I'm a closet grammar nazi, myself. I've just learned to ignore it the majority of the time. I'm also fine with things like ""Stang" or "'cept" or "prob'ly" (but I loathe "prolly"), at least in informal text such as chat or on a forum. I see these as a sort of "text visualization" of how someone speaks. In formal text, though, such as an email to a client or business associate, I expect and strive for proper spelling and grammar, and absolute minimal use of contractions.
I also love making up or mashing together multiple words, but I usually reserve those for friends and family who are used to how my skewed brain works.
But here's one that immediately flips my middle finger - "I'm going to sale my thing." It's "SELL", not "SALE". "I'm putting it up FOR SALE" or "I would like to SELL it". NEVER EVER EVER EVER EVER is it "I want to SALE it". Worse than 50 nuns dragging their nails down a chalkboard, in unison.