Do you like the style change?
Also, every instance above has happened to me while traveling to a convention.
A USB memory stick was mistaken for a bomb while traveling to Connecticon one year. I was brought aside and questioned for reasons they wouldn't tell me, then as they let me go, they handed a memory stick they took from my bag and suggested that I put it in with my checked luggage next time.
When I flew to Setsucon '08, I had a box of business cards in my backpack, which they explained to me looks like C-4 explosives on the x-ray screen.
As for the guard making fun of my business card, I had to empty my pockets for the metal detector when I was flying back from San Diego Comic Con '07, and I unloaded a pocket-full of cards. The guard picked up one of my cards, and inquired about what it was. I explained that it was my business card, to which he started calling it a "fake", because it was colorful and didn't look boring and plain, like the most people's business cards that pass through his metal detector. Apparently it really got to him, because he held up the line by telling me that nobody would take me seriously if I had a business card with my cartoons on it. He ignored me when I told him I was a cartoonist, and kept rambling on.
The Nintendo DS story is my favorite one. I went to Anime Boston '07, a good year after the DS's release, and the Boston Airport security guard removed the DS from my backpack, and inquired what it was. I tried explaining it to him, but he kept claiming that there was no such thing as a NIntendo DS, and wanted to know what I was really hiding in there. Fortunately, a buddy of his knew what it was and let me go.
I've never had good luck with Airport security. I know that it's their job to look for potential threats, but really, do I look like that much of a threat? But considering that my entire life, I've been perceived as a harmless, scrawny and non-threatening, I can't help but think that this is what it must feel like to be a "tough guy". Or just a terrorist, which isn't as preferable.
Conventions for 2009!
Setsucon 2009, January 17-18th! (Guest)
Katsucon 2009, February 13-15th! (Guest)
Animazement 2009, May 22nd-24th!
Anime Next 2009, June 12-14th! (Guest)
Anime Mid Atlantic 2009, June 19th-21st! (Guest)
Otakon 2009, July 17th-19th!
Connecticon 2009, July 31-August 2nd!(Guest)