For sheer bad delivery of a movie line, it has to be Tony Curtis in Genghis Khan.
He was playing the son of Genghis and he said in a honking, broad, new yawwwwk, bronx accent, "Yarnnda, lies the tent of my faddah ...." which should have sounded like, "Yonder, lies the tent of my Father" - but didnt .........
lol
Also, nearly every "quip" Roger Moore uttered in James Bond films, made me shudder, listening to the poor, wooden delivery and totally unfunny, unclever line ....