Why are the letters "M.O.A.I." used in Twelth Night in the letter Maria writes to fool Malvolio into thinking that Olivia loves him?
MOAI is part of an anagram, apparently. Go to the website linked below and then use the Find command (Ctrl + F on PCs) and enter those letters. The Find command then will highlight instances of these letters together. Read the whole section where the first highlighted sections are; then click on Next or the down arrow to find other instances.
Read them all, and then you'll be able to draw your own conclusion about its meaning!