Possible Clues:

• When doubled, an old sitcom sign-off
• When doubled, a greeting from Mork
• TV alien's word
• Half of a sitcom farewell
• When doubled, a sitcom sign-off
• Word said a lot by Mork
• When doubled, an old sitcom goodbye
• Word from Mork
• Half of an Orkan farewell
• Mork remark