Indeed. I used to teach LDS seminary (basically a religious course for LDS high school students during school hours where they are permitted to take an hour off to attend) for two years in Tucson. At one of the two schools I taught at, I received a report from my students that there was a boy at their school who made two small slits at the corners of his mouth and called himself the Joker. His scars were no where near as intense as Heath Ledger's character, but as this was just after TDK came out, it was obviously an attempt at emulation. One day at school, he had managed to smuggle in a knife and stabbed another teen, thankfully not too seriously.
Similarly, we all remember the Aurora, CO shooting at the premier of TDKR by a fellow also calling himself Joker.
I still love the Dark Knight Trilogy.
People just love to emulate evil sometimes. I'm not blaming Nanner or anything. I just thought it was an interesting coincidence.