Pop Goes the Weasel appears in a Walter Pardon song " he squared up to me and pulled my watch out he stole my beaver (hat) and damaged my snout
Pop goes the weasel to me he did say down by the Dark Arches under the railway" etc
the unfortunate had gone with a young lady, when he encountered her pimp, he ends up without clothes at all

the pimp,presumably pawned or fenced the said items in oirder to finance a night of drinking
Pop is to pawn with possible reclaim late
weasel probably slang for suit/tailor as the Tailors "Iron" would be heated up and resembled the front of a boat with a round snout. the Tailors ironing action would resemble a Weasel as it moved over the clothes