Optimus Prime T-Shirt: Get Your Geek Stuff Today

Transformers meets Back to the Future in this Optimnus Prime Themed T-Shirt. Only available today at TeeFury.com for 10 bucks!

Plants Versus Zombies, Zombie T-Shirt at ThinkGeek.com for 19.99

One of the funniest mashups I have ever seen on a t-shirt is this Masters Of The Universe Care Bears T-Shirt, available at 6dollarshirts.com for only 6 bucks!