Amanda and Mark had decided to go and buy supplies. Yes. Genuinely go out to a random store and get supplies for a trap. Sounds pretty weird, but you've gotta buy the parts somewhere. Amanda was driving and Mark was in the passenger seat. Billy the Puppet, for whatever reason, was in the backseat too, in a booster seat.

Mark: "You're seriously going to listen to this? I'm changing the music."

Amanda: "Don't you dare."