Ever since @Footsie started the fad (j/k, Footsie!), the to/too and even two thing has become pandemic here, along with the there, they're and their problem.
Whenever I encounter them here, I usually just gnaw on my fingers or quickly yank the batteries from my keyboard, but sometimes it gets the best of me, and I post these links:
But I think the one that incites my inner Grammar Nazi the most might be one I encounter often on hand-drawn chalkboards and signs, the use of apostrophe s to make a plural noun, to wit:
"Iggy Azalea Album's 4 Sell"
(A little bonus material there!)
or one I *actually* saw in Hee Haw Hell on the marquis at a kwikie mart:
FRESH RIPE WATERMELON'S