-んだ casual form

Question

I learned that the short form for な-adjs and nouns is だ, but I also learned that usually you wouldn't end a sentence with だ (usually it is dropped).

So when it comes to a sentence that ends with -んだ, would you drop the だ here too?

e.g. きのう、たべすぎるん。　vs　きのう、たべすぎるんだ。

Answer 1

In that case の as in のだ is not contracted into ん in Standard Japanese, in short, you say たべすぎるの.