I think this was a comment!fic. Sam and Dean decide to take a vacation via amnesia in Season 7 (and immediately decide they're boyfriends when they don't know who they are, of course). They run into Dick, and when Crowley finds them he's very upset that he'll be seeing them for eternity.

This was very cute and funny and I want to find it again!

Thx.

FOUND! Sam/Dean have amnesia and the rest is Wincestory: http://glovered.livejournal.com/47353.html?thread=472057#t472057