Coincidences (Attn: Xanadu. Now closed, except to Dean via phone/text)
Sam found out about the zombie plague the worst way possible; that is, meeting one in person. Everything was fine (the guy pointed him in the direction he wanted to go) until he tried to take a bite of his neck. Sam liked his neck intact, and he threw the guy off with a yell, only just avoiding an infecting bite. Being dead, a little thing like a judo throw didn't keep the zombie down long, and he got up and came for Sam in a slow, implacable stumble. Sam had fought zombies before, and he figured now would be a really good time to... run. Fast.
Sam needed a gun. He hadn't brought a gun, so naturally, he needed one. The first zombie caught up to him and picked him up like he weighed nothing at all. Sam went through a glass storefront and crashed into a counter. 'Ouch' didn't quite cover it, but when he got to his feet, he realized he was behind a convenience store counter; and there was a sawed-off sitting with a few boxes of cartridges just within reach. "...Coincidence," Sam said out loud, blinking.
The first direction he chose was the wrong one. More stumbling bodies blocked his way, and an alarming number of the stumbling bodies had blood on their lips. (Some had lips. Some had gaping bloody maws. Neither appealed to Sam.) "...I'm lost," Sam told them, skidding to a halt and backing up slowly with the shotgun lowered. "I'm just going to... go back that way."
"Braaaains," one of the zombies agreed.
"No, I really don't have any of those."
"Braaaains," another zombie insisted.
"Really, no," Sam said, backing up another few steps.
"Braaains," came a voice from behind. Sam whirled and fired. One zombie flew back into his neighbors, but more of them were coming from behind him. Surrounded, Sam backed up against a shop door. "Gee, more guns would be nice right now." Except all the guns were in the trunk of the Impala. With Dean. Sam hoped the guns were with Dean, anyway. At least he'd have more of a chance than Sam did.