So per miss_colombina's suggestion, I designed this:
The warning label mug, to protect you about evils! I even included my favorite warning, related to my favorite "pregnant women should not..." warning: "do not fill this mug with peanuts if you are allergic to peanuts."
You know, I didn't realize this, but I make nearly $70 a month lately from cafepress. It's almost all from people who go to the main cafepress website looking for stuff, not my website, which surprised me because for a long time I figured promoting your store and being popular would get you noticed. Not so. Try as I might I've never had a lot of website sales, it's just sort of there as a formality.
The trick is to have like 200 designs and something, somehow, will stick. When I made my store about spacefem.com, with useless blobs and planets, nothing really hit. But the thing with a premium store (which costs me $5 a month) is that you can just crank out designs whenever you're inspired to do so, and the store doesn't have to be about anything. That's why I guess I've got activity in there.
My top selling design by far is this sparkly rainbow. Do not ask me why it's so popular, I have no idea. I personally own no products with this design, but every month 10-15 items get sold.
The second highest selling is the t-shirt I made for DJs that says "Please avoid saying something stupid such as 'When are you going to play hip hop?'"