Boba Fett’s lines in ROTJ are precisely:
“Ugh. What the? Argh. Ugh. Argh.”
Don’t forget his two Aaaaagh! lines - once when flying uncontrolled towards the Sail Barge, then again when the AT-ST driver is thrown off the top of his vehicle by the mighty Chewbacca. Presumably out of sympathy for the poor guy.