I made myself an external battery set for my Compaq iPAQ. I took a Radio Shack(tm) battery case, attached a Radio Shack(tm) coaxial power connector to some Radio Shack(tm) speaker wire, insulated it with some Radio Shack(tm) black electrical wire, and filled it with Radio Shack(tm) Nickle-Metal-Hydride batteries.
Tried to take it (back) through the Portland Oregon airport after OSCON three years ago. Frigging moron bottom-of-her-class TSA inspector #1 decided it looked like a bomb. I foolishly said that I was uncomfortable watching her handle my possessions as if they might explode. She called the cops on me because I said the E-word. Frigging moron nearly-bottom-of-her-class TSA inspector #1 swabbed it and claimed that the spectrometer said that it had traces of C-4 explosive. I helpfully pointed out that the energy density of a modern battery was the equal of any plastic explosive. Not to be sexist, but a male TSA inspector came by and said "this is all stuff from Radio Shack(tm), what's the problem here?"
So the Portland cops came and bitched me out for having a bad attitude and making threats potentially subject to a $500 fine. I explained EXACTLY what I had said, offered to apologize and that was accepted. The airline representative had to be asked if he would allow me on his airplane. He was like WTF, and piss off a customer, oh, yeah, right "Yes, of course you're welcome to fly."