Student or Learner
What do you think "the upside of buttered bread" means?"Your uncle!" exclaimed Gunny with a smile. "Now that explains a few things. He told me all about you. Said you'd be showing up someday. He talked about you like you were the upside of buttered bread. Now it makes sense!"
Sounds as if it means 'something very good', but it's not an idiom I've met.
Same here. I've never seen it before, but it sure sounds like a very good thing.
Do you use the idiom "the best thing since sliced bread"? If so, I guess that buttered bread is even better than sliced bread.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.
It could be that the speaker was making up his own expression.