Bring me coffee!

My sister came over with coffee today and stayed for about an hour. People bring me coffee, a LOT! My best friend, Gin, always has a Starbucks coffee for me when she comes over. My friend, Rachel, always brings me coffee when she comes for a play date. So I've been thinking, is it because they want coffee themselves and feel guilty not bringing me some, or is it because they know how much I LOVE and appreciate the coffee?