It's been 20+ years but I loved this shirt for it's SQL agnostic-ity:
https://www.pinterest.com/pin/lol-code-geek-select-from-user...
(This shows the shirt you could buy once-upon-a-time from thinkgeek, which appears to be no more...)
I believe they used beefy-t brand shirts, which was like the nicest thing you could get for t-shirts at the time. (Personal opinion, don't @ me.)