If we're looking for a short, pithy statement which signals affiliation with the Less Wrong meme cluster, I think the standing all-time top rationality quote is a good place to start.
Personally, I've been hearing all my life about the Serious Philosophical Issues posed by life extension, and my attitude has always been that I'm willing to grapple with those issues for as many centuries as it takes.
-- Patrick Nielsen Hayden
That sounds a little too long for a T-shirt.
What are your best short witticisms, suitable for use on a t-shirt, bumper sticker, or similar location? Ideally something that might make someone reading it think, or get curious enough to ask about it. Simple in-group identification is fine too, though.
For context, therufs is spending today at the NC Maker Faire making t-shirts, and asked me for suggestions this morning. As I was still mostly asleep, I wasn't very helpful.