Tumblr is a weird place

No, that doesn't make gramatical sense

Okay i was wrong but greatpretender is wrong. You have to say Pope of potato.

It's because you are using a noun to describe another noun, so you need a preposition

We'll I'm fron Spain, and I'm pretty sure that that makes sense, but it may not mean what you wanted to :) (although it's a weird sense, no doubt hahaha)

For it to make sense it would have to be the other way round, una papa Papa

"Un Papa patata o una patata Papa" It works for me both ways

Well, we aren't from the same place, so gramatical rules aren't always the same... If you say you can say it like that in spain, i believe you