Zev Senesca is a Rebel pilot at Hoth who only speaks in Space Reverse Polish Notation.
The Enemy Let Slip Edit
Since the Rebels blew up the Peace Moon, they'd been on the run evacuating several bases with the Imperials suspiciously close on their heels, but managed to stay hidden on the ice world of Hoth for the past two years. One late afternoon on Hoth, Luke was riding a tauntaun while patrolling a sector outside the Rebel base, Han was riding another tauntaun patrolling a different sector, C-3PO, R2-D2, and Princess were in the command centre of the Rebel base, while Chewbacca was in the hangar working on repairs to the Millennium Falcon.
The next morning after Luke had gone missing and Han had gone back out looking for him, C-3PO was on hand at the base to translate over the radio for Zev Senesca, a hoverplane pilot who was flying around the next morning looking for Han and Luke, and Zev only spoke in Space Reverse Polish Notation. He was able to find and contact Han, which 3PO translated. Han asked Zev if he had any firewood.
Zev Senasca was present in the battle of Hoth, piloting his hoverplane as he and the other hoverplane pilots were fighting the armored tanks that looked like camels. Zev commented that the beating of the legs was like threading the eye of a needle, just before one of the camel tanks shot down Luke and Dak's hoverplane.