My own selfish altruism

I went out for dinner with some out of town friends. There was leftover pizza, so I took it home since they couldn't keep it. Outside of CVS I saw the guy that usually begs there and gave him the pizza. A casual reader would call this altruistic. However, there are some other important facts. First of all, I did not have gloves so whatever hand I was carrying the pizza with would freeze after 5 seconds out of my jacket pocket. Secondly, I was about to go into CVS and it would have been awkward to carry the pizza in. Third, I had not paid for the pizza (as evidenced by the fact that it wasn't consumed at the restaurant) so my attachment to it was less than if I had a sunk cost in it. Lastly, the guy was pretty obese, so deep dish pizza probably wasn't what a benevolent social planner would have given him.