Giveaways/contests for attendees of live in person NBA games and viewers at home.
Instead of only the traditional tshirts, towels, etc giveaways at live nba games that fans would receive when they attend, include nba topshot packs.
By giving a pack to the first x number of fans in attendance or every fan in attendance for that game it gives the fan a chance to experience the excitement of opening a new pack and getting one of their favourite players (the pack could feature players from the home and away teams playing that game)
This will generate more interest and buzz in the top shot universe and potentially draw in more users (those fans would then have to create a topshot account in order to get full access to the utility of the new moments they just got from attending the game)
During halftime or commercial breaks throughout the nba game there can be contests hosted in which all nba fans who are in attendance and watching from wherever they are can tweet or text to enter into a contest to win a free pack or moment giveaway.