The things I find.

[MortalMonday]

Yeah, they sell the shirts on the online Bethesda store. They have a whole run of unique vault boy perk shirts on their, and they sell one new shirt each month. Each shirt is only on sale for one week of its respective month. That shirt there was from last month, I believe. You can't buy it anymore sadly. They just put up this months shirt like 3 days ago. After this Friday, the new shirt will be gone too.