In Act III, scene 4, Macbeth has a lavish banquet. When Macbeth enters the room to join the table, Banquo's ghost is seated at his place, and a visibly shaken Macbeth speaks the the spectre: "Thou canst not say I did it: never shake thy gory locks at me" (50-51). Macbeth realizes that no one else can see the ghost except for him.
Ross immediately responds for everyone to rise to go home, that Macbeth must not feeling well, but Lady Macbeth attempts to cover for her husband. She tells everyone that Macbeth has had these fits "from his youth" (54).
Macbeth, worried that his companions are looking at him funnily, remarks " Do not muse at me, my most worthy friends" (86).
Finally, Macbeth is overcome by the ghost's appearance and reappearance. Lady Macbeth, genuinely concerned that her husband might lose control and confess, dismisses the dinner guests.
With Macbeth's bizarre behavior, the guests show their politely show their concern for his health. They are definitely puzzled. Lady Macbeth's quick thinking excused Macbeth from more serious questions the guests might have had about his sanity.