[Byron_the_Aussie]

He probably walked across a garden recently fertilized with nitrates. Possibly, in the airport carpark. I'd check first with the SF airport garden maintenance section to see if they've been using ammonium nitrates on the grounds recently.

[Johnny Crab]

Coulda' been some of those folks I don't respect....they shoot themselves in the foot a lot with their mouths and actions.....maybe this "shoe guy" missed with the real thing......swabbed his AK with his Nike?.....reloads by foot instead of by hand?....works in an ammo factory?....ok ok...It MAY be shoe bomber #3(#1 is blowed up in NY/wing/engine/tail-jumped-off-plane, #2 got busted by brave passengers and his stupidity, and this one screwed up too).