So, I recently got the annual "Can you do a t-shirt really quick for us" request, this year for an LDS Young Women camp. This one actually did come together rather quickly, and I was quite pleased with the result. Special thanks to the amazing art director (a.k.a. my lovely wife.)
I have found that the more last-minute the request, the more it is guaranteed to be accompanied with the caveat of "it doesn't need to be fancy, just something simple". Right... Of course, no one has ever yet emailed me and said "Can you design a crappy t-shirt for us, please?" I'll keep waiting for that email.