Auto Engine Diagram T-Shirt

You may not know a spark plug from an alternator, but you can be sure you'll at least look cool in this Auto Engine Diagram T-shirt ($23) from Slow Shirts. It has a hand-drawn diagram of an engine in case you ever forget where that pesky oil cap is. And since it's printed on American Apparel goodness, buy it a size bigger than you normally would — they shrink like crazy if you're a dryer type. [via Mighty Goods]