Definition from Wiktionary, the free dictionary
tu madre f
- (pejorative, slang) Similar to the English version, a catch-all retort; shut the fuck up. Literally: your mom.
- Que hora es?
- Tu madre.
The mother has a more sacred place in Hispanic culture, and invoking one's mother can carry more immediately negative consequences than might be the case in English-speaking countries depending on the specific person and relationship.