She took a giant shit on my face

She took a giant shit on my face.

I don’t really know that the sentence means.

There is a literal and a metaphorical meaning. Literally, she defecated (eliminated the contents of her bowels) on his face. That is unlikely. The metaphorical definition is more likely: “She expressed a strong negative feeling about him.” Either way, thank you for asking, although scatological, it is an amusing expression in English.