I think once they got to the point where they could take shots at themselves i truly fell in love with it. it's such a serious subject matter but at the same time, can be so utterly hilarious that it's just impossible to stop watching.
The bi-polar bear in the wishing well episode just about made me burst my spleen i was laughing so hard. The look on Dean's face just completely sells the "WTF"
I think the most unintentionally funny moment was Castiel on the phone with Dean. "This isn't funny Dean, The voice says i'm almost out of minutes."
Micha just has such a serious demeanor that it's gut wrenchingly funny. When they're in the brothel and he freaks out the girl his puzzled reaction is priceless.
I'm rewatching "The End" right now, when Past!Dean asks "Oh come on, you don't trust yourself?" and Future!Dean goes "No!" and Past!Dean just sit there and mutters "Uh....
Dick!"
or Chuck and his desperation for toilet paper
Does it show i'm a fan of dark humor?