Castiel trying out those pizza delivery man moves on Dean (I got a one track-mind, I know).
And if the show had not been continued to 6th season, I would've loved it if Sam and Dean had both died at the end of season 5 in some really epic, tragic, heart breaking way, the episode coming to a close with "Stairway to Heaven" blasting away (because Led Zeppelin is Dean's favourite band, but 'cause the usage of their songs cost so much, they've never played any on the show. I figured they could go a little over the budget if the whole thing was ending anyway).
