So my boss lets me leave an hour early yesterday to beat the impending rain storm, which of course means that the skies open up into heavy downpour about a mile into my ride. That's fine though. I can dry out. But almost soon as the rain starts pounding down, I hear something banging around my rear wheel and then BOOM! my rear tire is flat just like that. Sucked. Just walking it the half mile to the subway got me drenched to the bone.
Was feeling grouchy, so I took a sick day and got it fixed. The bike guy found this lone jagged piece of metal stuck in it. Might have been some weird nail or possibly part of a machine. Tore up the tire as well as the tube, so replaced both. He said they always get tons of flats to fix after a rainstorm. Shit just gets stirred up or something.