This expression is full of imagery. Te cayó la voladora literally means "the flying one fell upon you." It is a sophisticated version of the more direct expression te cayó la verga, which literally means "the penis fell upon you." Both expressions are used to convey terrible news for the subject upon which the penis is said to fall.
Automovilista: Oficial, la verdad es que no sé qué están haciendo estos dos kilos de marihuana en mi auto.
Oficial: Con todo respeto jefe, ya le cayó la voladora.
Driver: Officer, honestly I have no idea what those two kilos of marijuana are doing in my car.
Officer: With all due repect, sir, your so screwed.