I just love how quickly this joke became overused. I feel like people were making it for only a week before everyone and their mom knew it and started getting tired of it. Heck , now people are going all hipster and arguing over who got tired of it first!
The joke is the hats/skins I'm thinking. Portal 2 was great fun, I think it's just that it went from a pretty serious thing, to much more room for goofing around. Between the ridiculous colors/clothes you can put on Blue and Orange, and the amount of dickery we now pull on each other with our portals.