machine gun mouth
A machine gun mouth is someone who talks so much and so fast it feels like you're being shot with words from all directions.
My brother rambled about his video game achievements for an hour. I wanted to scream and hide under my bed.
My friend started telling me about his pet goldfish's life story. I felt like I was drowning in fish talk.
My boss started giving me a lecture about the coffee machine. I wanted to throw my coffee in his face.