Not me personally, but my roommate:
I'm sure many people here know of Zero Punctuation, and the 'Pants on Head Retarded' slogan and T-Shirt. My roommate was wearing the shirt, walking to campus one day when this little old lady who works in the residence cafeteria walks by. She has some kind of issue with her motor skills, making walking difficult for her, and her son has some other kind of medical issue from birth (I don't know specifically what the disease is or what measure need to be taken to cope with, but I digress). She recognized him as he had live in residence for three years prior, and they smiled at eachother. She then saw the shirt he was wearing, in which the word 'retarded' is in huge black letters on the yellow background, and immediately her face turned sour as she passed by him on the sidewalk.
Bad day to wear the shirt :P