It’s Dominican slang that implies that you fuck your own
mother, that’s to mean that you’re such a
dirty,
nasty and disgusting person that you’re even able to do that.
Although most of the times, when said to other people, it’s taken as a offensive, it’s common hear Dominicans say it as an interjection.
Qué rapa tu
madre tú ere, loco! Cómo tú te vas a comer
la comida mía? (What a rapa tu madre
you are, bro! How dare you to eat my food?)