I Solemnly Swear Tee
Wand not required
There are so many phrases to remember at Hogwarts. How can you keep them all straight?
For those of us who are forgetful, it's always good to have a little something to jog your memory. Forget how to use the Marauder's Map? Read the front of your shirt. Forget how to hide the contents? Somebody else will have to read the back of your shirt.
Front of this black, 100% cotton shirt reads "I solemnly swear that I am up to no good." Back reads "Mischief Managed."