Sirians may or may not have two arms, so whether or not they could actually wear the shirt remains a question, but hey, it would make a great wall hanging for back home, if they have walls. We're not certain if we can actually sell these shirts to the Sirians. There is no rate of exchange, that we know of, between Sirian money and U.S. greenbacks. The Sirians may even have evolved to a point where currency is unnecessary. But heck, we'd be willing to trade.
Tee shirts for technology.
The possibilities could be huge.