Yeah, that's right. Fan blades. If there's a cultural or scientific thing that this t-shirt is referencing that I'm not getting, someone please leave me a message and enlighten me. Because this particular t-shirt is a pain in the tookus (excuse my Yiddish) to find. Thus far I've come up empty handed in my searches. Please, internet, let's join forces to hunt this sucker down!
Featured in The Big Bang Theory episodes
S01 E02: "The Big Bran Hypothesis"