Yo cago en la leche de tu madre 

I think this is a misquote, it should be 'Me cago en la leche que mamaste' which means "I shit in the milk that you suckled from your mother's breast"
Lovely expression, isn't it? (used widely as 'Me cago en la leche')
The above I have never heard, and anyway this is an English slang dictionary not an Eng - Span one.

Spanish speaker one: Acabo de romper tus gafas (I've just broken your glasses).
Spanish speaker two: Me cago en la leche que mamaste, cabróncete de mierda. (I shit in the milk you suckled from your mother's breast you shitty/fuckin'little bastard.

Yo cago en la leche de tu madre by ant July 18, 2004

Yo cago en la leche de tu madre 

Spanish for "I shit in the milk of your mother"

Juan, yo cago en la leche de tu madre.

Yo cago en la leche de tu madre by montana is gay May 11, 2004