Possible Clues:

• Half of Mork's sign-off
• Half of Mork's farewell
• When repeated, Mork's sign-off
• Sitcom sign-off word
• Half of Mork's signoff
• When repeated, Mork's TV sign-off
• Half of Mork's greeting
• Half an Orkan farewell
• Half a Mork-to-Orson farewell
• Half of Mork's goodbye