Lots of my blog readers appear to be up to no good.
The first is Cori:
The second is Samantha, whose tattoo is done in "James Potter's (prongs) handwriting":
Finally, Chloe, who explains:
Under regular light, it looks like a blank scroll (almost) with the three stars that appear on every page in each book. But under a black light, the quote lights up: "I solemnly swear that I am up to no good." (I couldn't get the best picture of it or angle with my scorpion finder light, but you get the idea.)
This is the password to the Marauder's Map, first appearing in Harry Potter and the Prisoner of Azkaban.
"Messrs. Mooney, Wormtail, Padfoot, and Prongs
Purveyors of Aids to Magical Mischief-Makers
are proud to present
THE MARAUDER'S MAP"
—The Marauder's Map