"Pamela Barnes" was the actress who played the third blonde replacement chick on "Three's Company" (after Suzanne Somers and Jennilee Harrison). And "Pamela Barnes" on SPN is the one who proposed the threesome.
I am, quite likely, totally grasping at straws with my lame pop culture knowledge, but I thought I'd share.
ETA: I am even more epically lame! I got it wrong! I knew I remembered the name, but the person I was thinking of was PRISCILLA Barnes. However, the same part of my brain was tickled! Because PAMELA Barnes was...
the maiden name of Bobby's wife on "Dallas"! The chick played by Victoria Principal. The one who found Bobby in the shower after that whole season that was all "a horrible dream"! MOAR Cheezy '70s/'80s TV! PLUS! The second season premiere (or anywhere) "Dallas" reference! Ribbing the boys? Or just Kripke's misspent childhood (much like mine) with too much bad TV? Both?