Nixon's Head: The Loot, the loot, the loot is on fire!
Nixon's line was a parody of the song "Fire Water Burn" by done the Bloodhound Gang. In fact the way Nixon said it is exactly the way the song goes on the part of the song that says "The roof, the roof, the roof is on fire".
It could also be interpreted as a parody of the Coal Chamber song "Sway", where the same line "The roof! The roof! The roof is on fire!" occurs.