I do, unfortunately, but not often.
Whenever I cook, I either make a small amount of something or stick to meals/items that I won't get sick of and/or can freeze (for instance, the rockin' split pea soup I made the other day was divided into small containers and put in the freezer for when I'm in a soup mood), so I very, VERY rarely throw out cooked food or leftovers. I do, however, have to throw out fruits, veggies, or other perishables on occasion. I hate doing it, and try my hardest to shop in a way that won't happen, but I live alone and sometimes get overly ambitious at the grocery store. I'll end up buying way more than I have any chance of eating because it looks good. Either that, or I'll stock up on various items with the best of intentions and then get too busy to cook -- eat dinner out a few nights in a row and next thing you know I've got a fridge full of green beans and broccoli that needs to be tossed.