I'm sure it's all the fault of that episode 'Blink'.
If you remember, one of the characters said that he had 'The Angels have the Phone Box' on a t-shirt. Well, sure enough, 24 hours later lots of designs were hitting the internet. Here are just some from Cafepress.
Then at the end of last season, there were the Master themed shirts;
And then with the library two-parter, came this little gem;
I'm sorry I can't link to the images, but there is some great stuff there if you take the time to search. You just have to try different keywords as 'Doctor Who' doesn't work. Try 'Who Doctor' in stead.
