How do you kill Leviathan? Bobby passes some advice along to Dean in this scene from Supernatural.
Added:
Look out, Sam and Dean. A major double cross appears to be on the way, based on this Supernatural promo.
Added:

Supernatural Season 7 Episode 22 Quotes

Dean: Don't say pie.
Sam: Definitely pie.
Dean: Bastards.

Dean: Ok, I've read this more times than the Playboy I found in dad's duffel.
Sam: Anna Nicole?
Dean: Anna Nicole.