I got the white one and there is a bash + base64 code behind it and i got curious, and on their website they said
On the back of the T-shirt is real code. It’s a reference to Linux, the open-source language of the internet.
With the help of OCR and 2 hours of my time I somehow manage got a usable base64 code
eval "$(base64 -d <<<'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