Another reason why it's a terrible idea:
The idea is to sell items to Newgrounders, to appeal to all Newgrounders. I imagine these days users from 2005+ outrank users from before at a ratio of like 10:1, if not more. So you're not going to get too many users buying those t-shirts, besides mods of course.
Use this topic as an example;
There are just 5 users posting who have a sign up from 2004 or earlier, and one of them is YOU. Now look at the rest of the posters sign up dates.
Really gonna sell well innit.
Did your life flash before your eyes?
Cup of tea, cup of tea, almost got shagged, cup of tea.