Opportunity is missed by most people because it is dressed in overalls and looks like work. - Thomas Edison
It's just one shirt? I'd do it. Who's going to sue you? But let your conscience be your guide.
assuming the original is copyrighted, the squid version is not a parody, but a joke. Parody has to make fun or mockery of the original for the purpose of making a statement. For example, "yummie Brownies" is not a parody of the cleveland Browns, but a clever joke. Having an image of a brownie and a Browns helmet (or logo) then saying that these brownies suck would qualify for a parody. In this case parody would be saying "out of tune squad" if they were not performing well. . . Here's a quote from the web:"A parody is a work that ridicules another, usually well-known work, by imitating it in a comic way." (emphasis is mine).*pierre*http://fairuse.stanford.edu/overview/fair-use/what-is-fair-use/
What about something like this?This isn't "parody" but Jason Lee isn't a nobody either.
I had a recent conundrum around purchasing stock art. The regular licence vs extended license issue. I am convincing customers to pay for stock art rather than copying, but the fine print says that if it's going onto tshirts or a product being sold then it needs the extended license which is way, way more pricey. Seems the lines get a bit blurry here...