Examples? Cripes, there's quite the variety. I have a t-shirt with the title 'Avatar' on it. That was the working title for a third all-CG Terminator movie. I got the shirt at SIGGRAPH in '96. Some programmers have shirts with formulae printed on them that they apparently find funny. I have a Capcom shirt with Maximo on the back. There are dozens of faded shirts with game mag titles on them. I consider my 'Onion' t-shirts geeky. Right now I'm wearing my SVX Network t-shirt, and that can't escape a rating of 'geek.'
Oh, and I have a Yanni t-shirt. That's not geeky, it's just funny. I used to work on the local crew at the Bradley center in Milwaukee and one of the concerts I set up was Yanni's. I pushed him out of the way with a big, heavy lighting truss.
Yanni is very short and he smells bad.
Am I off-topic enough yet?