"Speak Passphase aloud" is a mission objective in the quest Dwarven Allies in Tiny Tina's Assault on Dragon Keep DLC
Walkthrough[edit]
After placing the letters from left to right to spell out "Fart" head to the middle and interact with it to speak the phase
Dialogue[edit]
Vault Hunter: "Uhm ... raft."
Lilith: "Was that not the password?"
Mordecai: "Ugh, god ... I just figured it out."
Brick: "So say it."
Mordecai: "Fine. It's (sigh) ... 'Fart."
Tina: "AHAHAHAHAHAHA"