Why does Agustín say "miércoles" in the Encanto movie? What does it mean?

Question

In Disney's Encanto there is a scene which involves Mirabel, her father Agustín and her cousin Dolores. Mirabel and her father have discovered a secret which Dolores, thanks to her awesome hearing, is also aware of. Dolores then runs off and Mirabel states that she is going to tell everybody the secret, to which her father Agustín says:

—¡Miércoles!

This expression is left in Spanish in the original English version as well as in other versions such as Portuguese, Italian, French, German and others. Only some versions such as the Japanese one do translate the expression, but they do not translate it literally to wednesday, as it must have another, different meaning in this context. So, as that expression may be something only the Spanish speakers are able to understand, what does it mean and why is it used here?

Answer 1

In that context, miércoles is a minced oath. That is, a mild, inoffensive expression which replaces a stronger, more offensive one. In this case, the word to replace is mierda. It has the same effect as saying shoot instead of shit, which would be the literal translation for mierda.

In this case, the initial mier- is conserved but the original word is replaced with a different one that starts with the same group. This expression is widely used in the Spanish speaking countries, and even registered in RAE's Spanish Dictionary in its second meaning. In short, Agustín is just expressing his annoyance to know that Dolores also knows.

You can know more about this and other minced oaths in Spanish here: Minced oaths in Spanish.