Simple: Zombies are easy to break. Just tie em up, apply some violence to them and voila.
Peashooter: Speak, gimme what you know.
Zombie: Brains?
P: No, not brains. Anything else
Z: Braaaaains.
P: Can you please speak correctly? In English? Not whatever that "brain" language is.
Z: Brains?
P: SPEAK, DUMBASS! SPEEEEEEEAK!!
Z: Brains, brains!
P: YOU WANT ME TO FUCKING BEAT YOU HUH? SPEAK FUCKING REAL WORDS!!
Z: B-b-braaaains?!
P: COME HERE BITCH! (grabs zombie) (slaps face) SPEAK! SPEAK, MORON!
Z: BRAAAINS!!
P: FUCKING SPEAK!! (slaps face) DICKHEAD! (punches face) COME ON ASSHOLE! (punches face harder) SPEAK ACTUAL WORDS! (continuously punches the zombie's face until they bleed some pus)
Z: FINE, FINE! I GIVE UP! OK I'LL TALK, I'LL TALK! DAMMIT!
P: You SHOULD'VE done that shit earlier, coward.
Z: O-OK, what do you want?
P: EVERYTHING YOU KNOW!
Z: A-a-a-alright then, I-I-I'm gonna tell you thaaaaat, please just don't hurt me now!