Dean and Sam went up to Bobby's front door and knocked, knowing Bobby would keep the door locked at this time of the night. There was no answer, and Dean could see the light on in Bobby's living room, so he knew he was home. It was cold out so they decided to use the hidden key to get in. Bobby wouldn't mind, and he was probably just attending to duty in the bathroom.
They walked in and called out – Bobby – we're here," but no answer. In the living room Bobby's lamp was on next to his favorite chair and his plaid blanket he liked to use on his lap was hanging over in a weird fashion – usually when Bobby got up he just threw the blanket over one of the arms, but it was laying over the seat of the chair, like it would be if Bobby were sitting there.
Sam checked upstairs and Dean checked the rest of the downstairs – nope – Bobby wasn't paying a visit to the restroom – and the Winchesters were a little concerned. Bobby's truck was still outside.
"Maybe he suddenly needed something from the salvage yard and went to get it," Sam suggested.
"At this time of the night?" Dean said.
"You have any other bright ideas?" Sam asked.
"I don't know. You wait here, I forgot something in the car." Dean stepped outside and approached the car and got into the passenger seat. What he wanted was in the glove box.
"Dean, what am I doing in your car?" The voice came from the backseat and Dean's head nearly hit the ceiling he was so startled.
He looked back and there was Bobby sitting there right in the middle of the back seat.
"Bobby! What the! You scared the Bejezus out of me!!" Dean shook his head and laughed. "Very funny, Bobby. What did you do, hide in the dark? You had us worried, you know!"
"What are you talking about Dean?" Bobby said. "All I know is that I was sitting in my chair, looking at this strange old journal and then your headlights were coming up the drive, I close my eyes for a second, and then I am here in your car."
"Oh yeah, right, Bobby, what is this, April Fools day? Quit jerking my chain. I'm not falling for it. Besides, we scoured your house looking for you for several minutes. Did you just sit here in this ice cold car waiting for us? What if I hadn't come back to the car and just waited for you to come in? You got lucky that I even came out here."
"This car isn't that ice cold you idjit – it's still warm from the heat you were blasting on your trip. And I can't account for the time lost, but to me it's like I just got here. I mean I opened my eyes from the headache, and there I was looking at you from back here. Now quit accusing me of playing a joke on you – I'm starting to wonder if you guys found me passed out in the chair, and put me in here as a joke!"
"Hell no! For one thing – Bobby – you're not that light." Dean realized Bobby looked pretty freaked out. "Let's get in the house and discuss this."
Bobby got out, looking around all over the place as if to make sure he didn't find himself suddenly in a place stranger than the back of the Impala.