Yeah, I figured that out, too. It's all a Modell's advertising scheme. Not really a "Celtics" shirt, more of a Modell's shirt. "Beat LA" is a fine sentiment in many ways, but I'd prefer to wear Celtics colors; I don't need "LA" on my shirt. It's not a trademark, it's just that Modell's wanted a version of their slogan on the shirt. Their regular "Gotta Go To Mo's" is on the back.
It's not about the Lakers, it's about the CELTICS. I wear Celtics wear to all games, usually a green shirt, always a Celtics shirt, always a green shirt and/or cap. I didn't wear the Modell's shirt, but it's already in good hands; someone who could not make it to the game and likes the shirt.
The funny little green "foam fingers" were weird. It's the first time I've seen a foam finger that was life size. All in all, two pretty worthless giveaways. Green shirts with the Celtics logo are much better. But the real party favor is the win; promotional freebies are pretty insignificant when compared to the importance of a CELTICS WIN IN THE FINALS!