Do you have a funny t-shirt idea?

For my niece's 13th birthday, I'm going to personalize about ten shirts. She loves funny t-shirts that say things like, "There is a fine line between genius and insanity. I have crossed this line." and "Stand back, I'm going to do science." She's a proud geek and loves geeky shirts too. I'm looking for lines that are funny and appropriate for her to wear to school. She is turning 13.