When the name of the play is spoken in a theatre, tradition requires the person who spoke it to leave, perform traditional cleansing rituals, and be invited back in. The rituals are supposed to ward off the evil that uttering the play's name is feared to bring on.
The rituals include turning three times, spitting over one's left shoulder, swearing, or reciting a line from another of Shakespeare's plays. Popular lines for this purpose include, "Angels and ministers of grace defend us" (Hamlet 1.IV), "If we shadows have offended" (A Midsummer Night's Dream 5.ii), and "Fair thoughts and happy hours attend on you" (The Merchant of Venice, 3.IV). A more elaborate cleansing ritual involves leaving the theatre, spinning around and brushing oneself off, and saying "Macbeth" three times before entering again. Some production groups insist that the offender may not re-enter the theatre until invited to do so, therefore making it easy to punish frequent offenders by leaving them outside.
A portrayal of the ritual occurs in the 1983 film The Dresser, in which Sir is the offender, and Norman, his dresser, officiates over the propitiation.
The cleansing rituals have been parodied numerous times in popular culture, including in Blackadder, Slings and Arrows, The Simpsons, The West Wing, and Make It Pop. For example, in the Blackadder episode "Sense and Senility", a parody ritual performed by two actors involves slapping each other's hands pat-a-cake fashion with a quickly-spoken ritual ("Hot potato, orchestra stalls, Puck will make amends"), followed by tweaking the other person's nose. In Slings and Arrows, a guest director mocks the superstition by saying the word "Macbeth" onstage, spins around, and falls off on her third spin, resulting in an injury that takes her out of commission for the rest of the season. On The Simpsons, the core five are invited into a performance by Ian McKellen (in Scottish attire, clearly in the title role). The family keeps saying the title, which only makes more bad luck strike the actor, including lightning striking him and the "MAC" falling from the signage (leaving the "BETH").
Patrick Stewart, on the radio program Ask Me Another, asserted "if you have played the role of the Scottish thane, then you are allowed to say the title, any time anywhere."