I tip 20% in restaurants and 20% for delivery. I don't tip for takeout (that is, when I pick it up) because I thought one didn't, but I always feel a little awkward and uncomfortable when there is a place on the receipt for a tip and I don't leave one.

I'm confused in this thread because it sounds like people are using the word "takeout" to cover a wide variety of different situations -- getting a pizza delivered, ordering Chinese food by phone and then picking it up, even getting a burger at a fast food restaurant. Aren't these usually all handled differently?