The ass cup is the result of a second brew, particularly of a cheap brand of coffee grounds. Most who brew ass cups are too ashamed to admit they are so cheap that they double brew their cheap-ass brand of ground coffee. For sure, you would never give an ass cup to your friend (but maybe your enemy). The ass cup, that second cup, is so named because it tastes like ass, smells like ass, and even looks like pitch black ass water. You know you shouldn't, but you are just such a cheap bastard that you keep thinking the ass cup of coffee isn't so bad, but it always is when you try it. It is ASS.
I was sitting quietly, watching the birds, sipping on the ass cup I had just made, and swearing that I would never make another one.