There was a time where carry a Shell on your back look funny but not anymore. Not when the TMNT taken the world by storm in the 1980s, Super Mario and Dragonball manga rock.
Now having a Shell bag look cool! How cool? Check these out!
TMNT Shell bag!
The bag have various compartments to hold different stuff in place such as books and even tablet.
The back of the bag even have the TURTLES sewed on it. Look comfortable. The best part is it comes with 4 color TMNT masks so you can cosplay if you like! More at Think Geek
If you think this could be rather appeal more for children, then you can try getting this King Koopa's Spike Shell Bag
Black leather bag which can hold 16" laptop really can kick some Punks. Don't worry about the Spikes as they are soft. More at ThinkGeek
These are cool bags!