It's selfish to only think about yourself.
Kyle is married to Heidi and just won a $200 gift certificate for a fancy restaurant.
Kyle wants to use his prize.
Kyle takes Heidi to the restaurant, and they both enjoy a nice meal together.
Kyle, having never been to an upscale restaurant goes alone and orders himself the most expensive items on the menu.
Heidi thinks it was nice of Kyle to take her, and he feels generous.
Heidi sees Kyle as selfish, and he feels like a glutton afterwards.