What are some puns that Feste uses in Twelfth Night?

A pun is a play on words which reveals a clever and often
humorous double meaning for a word or the sound of a word. Puns are widely used in
literature but in the twenty-first century they are sometimes cliche and so they do not
always achieve their desired result. In order to benefit from a pun, the response needs
to be spontaneous; otherwise the joke is often lost when the implied meaning is not
shared.  

Shakespeare uses puns generously in his works and
in Twelfth Night, Feste the Fool or clown is an intelligent and
astute man, a keen observer and well-placed to recognize weakness in others. In Act I,
scene v he quips "Better a witty fool than a foolish wit" (33) having just bantered with
Maria over the benefits of being hanged and therefore avoiding "a bad marriage" (18). He
says "I am resolved on two points" (21) and Maria shares this pun when she comments on
the "points" used to hold up his trousers.

When Olivia
instructs "Take the fool away" (35), Feste immediately responds that she must mean
herself. He says, "Do you hear, fellows? Take away the lady." The "fool" is a
duly-appointed jester or entertainer and no fool at all but he is again using a pun
suggesting that Olivia must be the real fool and he can prove it. He suggests that
Olivia's state of mourning for her brother is misplaced as he is surely in heaven not
hell; thus proving that she is foolish as why would anyone mourn for a soul that is
peacefully in heaven. 

When Feste talks to Viola and she
asks him about his tabor or drum and whether he "lives by" it (III.i.2), she is
inquiring whether it is essential to his profession and from which he makes a living but
he uses a pun in taking her intended meaning of "live by" and advises that "I live by
the church." He means that he lives next to the church and not that he is a clergyman;
thereby purposefully misleading her. Viola is happy to continue the thread and
recognizes Feste's sharp wit.