Code:
 if (guest isin $nick) { do somthing }
 else {
  do somthing else
}

And you dont need "haltdef" in more then one place.
Code:
on ^*:quit: {
 haltdef
 ; rest of code here
}

if ($me != tired) { return } | else { echo -a Get a pot of coffee now $+($me,.) }