It looks like the Irritable Owl Syndrome design comes not just on a mug, but also on shirts and a number of other items available from CafePress . While it's not explicitly Harry Potter-themed, the mail-delivering owls are some of the most memorable members of the universe in which the books take place.The gift was doubly appropriate because July 31 is Harry Potter's fictional birthday as well as Rowling's actual one. It was also the launch date for the published script of Harry Potter and the Cursed Child Rowling's son, David Gordon Rowling Murray, seems to have a mature relationship with his mom for a 13-year-old. And the fact that she can laugh about it, even while calling it "unacceptable," pretty much confirms that she's the coolest mom, ever.