You know when you have a craving for something. You're not hungry particularly, but there is something that is constantly on you mind and you'll just keel over and die if you don't eat it this very minute...well we have an expression for that...

a craving for vinagre chips as an example...

I would eat vinagre chips on a pig's back.

Meaning you crave it so much that even if they were on a pigs back you'd eat them anyway.