SNL's third presidential debate parody

Last night's "Saturday Night Live" parody of Wednesday's debate mocked John McCain for having Joe the Plumber as his "imaginary friend." The sketch comedy show's primetime edition was seen by 8.6 million viewers and earned a 4.1 rating, dropping 20% from last week's debut.

SNL's previous debate spoofs:

>> McCain-Obama second presidential debate

>> Palin-Biden vice presidential debate

>>McCain-Obama first presidential debate

Related: Full Thursday night primetime ratings here. John McCain's appearance on David Letterman here.

Update: Sarah Palin visits SNL