So, suppose I gave you and your sister a hundred rupees each. And I say, go to the market and buy yourself something. She buys a frock for herself and you buy a shirt for yourself.
Now, let's say you bought something and your sister asks to see it. You tell her to go first. She shows a shirt that she has bought for you. And, then you smiles and shows her a frock that you have bought for her. Either way you were going to get a shirt and she a frock. But the feeling you get from giving... It's magic.