If you plan on flying a TARDIS you have to have a manual. Especially if it is one of those old Type 40s. Those are old and tricky to fly. This Haynes Guide to the TARDIS T-Shirt puts the manual on your chest.
Now you will at least have a quick reference to the cover of the manual at least. If the Doctor had a manual, he might even be able to land on target for once and not be late.
This awesome shirt is just $19.99 from ThinkGeek.com.