[citation][nom]gwolfman[/nom]I agree with Calvin_laing, won't the ink fade and/or wash out?[/citation]
If you use regular printer ink? Absolutely. Sunlight would bleach it and washing simply remove the colours. If you'd want to show up on, say, a party with an original shirt, you could take an old white shirt and print something on it, but more than that is beyond the capacity of regular ink.
But maybe there are companies selling waterproof high quality printer ink? But if there are, it's probably so expensive it's cheaper to find a local business that prints shirts.