I'm not sure why there was a human sock in Rarity's trash can in the episode "Party of One", but I feel like this scene happened shortly after the Rarity and Pinkie Pie's exchange. Also, this may be canon until proven otherwise ^^
This is probably the oldest meme on the show to date, but it's still just as funny as it ever was! I love how Lyra is all like "SWAG" with those shades, and how Shoeshine and Bon Bon just appear to be perplexed by both the sock and their friend's behavior. Good one!