Same shirt, different design. That's exactly what you'll end up rocking every morning with the Brick Construction Shirt, a nifty little outfit that you can deck with your favorite construction blocks of choice.
Sporting a baseplate right on the chest area, you can pile on the bricks to form as many awesome figures as you like. Write messages, build shapes...heck, you can put an entire LEGO castle in there if you want to. Just remove it the next day, put on a new design and tell everyone it's a different shirt - no one will notice (yeah, right).
The Brick Construction Shirt can work with a wide range of construction blocks, including LEGO, Mega Bloks, PixelBlocks and K'NEX Bricks. You can remove the baseplate when you finally decide to wash the shirt (you know, like when it's Sunday). It doesn't come with its own set of modular bricks, however, so you'll have to pull them out from your own collection.
Naturally, this would be ideal for flat designs. Based on the product photos, though, the shirt seems to hold up to even the larger, heavier structures like cars and space vehicles. May I suggest building a Piranha Plant bursting out of your chest? Or a horizontal skyscraper if you want to get really obnoxious.
The tacky but undeniably cool Brick Construction Shirt is available from ThinkGeek for $18.