When even groan-inducing American newspaper comic strips are making reference to Doctor Who, you know its influence has reached far and wide into the American psyche. Yesterday’s Sally Forth:
*groan* Nobody calls the Doctor “Doc.”
More Sally Forth here; the strip’s home page is here.
(Thanks to Sherry and Dave, who both independently sent the link. If you stumble across a cool Doctor Who thing, feel free to email me with a link.)
More recently, the dad was holding a mug with the DW TARDIS symbol on it.