What does 耳 mean in these contexts?

Question

What does 耳 stand for in these sentences?

“ パン耳どしてますか” From what I know this means “do you have any bread?” I wanted to use it in another way, just to see if it would form a similar sentence translation, so I changed “pan” to “gohan” (ごはん耳どしてますか), but instead I got a translation of “Do you listen?” I want to know what mimi/耳 stands for in this context.

I’m aware not all character positions are interchangeable, just curious about the characters (耳) meaning in a sentence. Thanks!

Update: Thank you Foogod for the answer! I didn’t process that “bread ear” could refer to the crusts. Thank you l'électeur for the updated explanation, it definitely helps a lot!

Answer 1

「パン耳どしてますか」

does not mean:

“Do you have any bread?”

That is not even close if I may be completely honest.

「耳{みみ}」, in this context, means "edges" or "crust". We say 「パンの耳」、「ピザの耳」、「紙{かみ}の耳」, etc. (紙 means "paper".)

「ごはん（の）耳」 makes little to no sense as rice has no edges.

「どしてますか」 is a very informal way of saying 「どうしてますか」, which means "What do you do with ~~?". So, 「パン耳どしてますか」 means "What do you (usually) do with bread crust?"

In other words, it is asking "Do you use/eat the bread crust in any way or do you just throw it away?"

Thus, 「ごはん耳どしてますか」 makes no sense and it certainly does not mean “Do you listen?”. Wonder who told you that.

Answer 2

パン耳 ("bread ear") is actually an expression that means "bread crust" in Japanese, so this actually means "Do you have any bread crusts?"

This is why you can't replace パン with other words, because this is a special meaning for 耳 that only works when combined with パン.