Give an example of a pun and a malapropism from Twelfth Night and explain it, providing line numbers.

Here is an example of a pun from Act I, Scene 5 of the
play.  Maria and Feste, the fool, are talking to each other.  They
say:

• href="http://www.opensourceshakespeare.org/views/plays/characters/charlines.php?CharID=MARIA&WorkID=12night">Maria.
  You are resolute, then?
  

• href="http://www.opensourceshakespeare.org/views/plays/characters/charlines.php?CharID=FESTE&WorkID=12night">Feste.
  Not so, neither; but I am resolved on two points.
  

• href="http://www.opensourceshakespeare.org/views/plays/characters/charlines.php?CharID=MARIA&WorkID=12night">Maria.
  That if one break, the other will hold; or, if both
  315
  break, your gaskins fall.
  

The
pun here is on the word "points."  Feste is using it to mean a point like some idea that
he has decided on.  But Maria is using it to refer to the points of his suspenders --
the place where they are attached to the buttons on his
pants.

You can find a malapropism in Act I, Scene 3.  In
this case, it is Sir Toby Belch talking.  He says

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By this
hand, they are scoundrels and subtractors
that say so of him. Who are
they?

The malapropism is
"subtractors," which ought to be "detractors."