背锅 uses 锅 (pot) as a metaphor for blame - you're carrying someone else's heavy pot on your back. 背锅侠 (pot-carrying hero) is a humorous term for someone who always ends up being the scapegoat. The opposite is 甩锅 (throwing the pot = passing blame).
memory
Imagine carrying a huge heavy wok on your back that someone threw at you - that's the weight of undeserved blame.
