Me duele el pecho pero me lo echo

[Glen]

Just now heard this, I believe in the context of someone at the dinner table who wants to apologize for taking the last remaining item of food or drink. Right?

[AngelicaDeAlquezar]

Never heard it before, but it could suit the context.

In Mexican slang, "echarse algo" can certainly mean to eat/drink it.

· Vamos a echarnos unas chelas, ¿no?
Let's have some beers.

· De camino a la casa me eché unos tacos.
I ate some tacos when I was coming home.

[chileno]

In Chile, more or less the same.

Me duele el pecho (en el alma) pero me lo echo (al pecho)

It is going to hurt me, but I'll take it anyway.