The last time we added a shirt to the reddit store, we offered a free bobblehead to the first few who bought a shirt and photographed their receipt (with alien doodle), a Richard Stallman picture, and an image with no fewer than 3 hamsters. Pretty standard, really.
Now there's a new shirt on the reddit store, but while we come up with something ridiculous you can do to get a free bobblehead, take a look at the last submissions. They are most excellent.