and if you really wanted to be annoying you could have it mimick them in all the channels your in with them by removing the %channel and changing the on text/on action command to * instead of having the %channel in there to check the channel.

#mimic off
#mimic end
alias mimic {
  set %mimic.person $1
   .enable #mimic
  echo -a 4,1Mimicing $1
}

alias mimic.off {
  .disable #mimic
  echo -a 4,1You are no longer being annoying %mimic.person
  unset %mimic.person
}

on *:text:*:*: {
  if ($group(#mimic).status == on) {
    if ($nick == %mimic.person) {
      msg $chan $1-
    }
  }
}
on *:action:*:*: {
  if ($group(#mimic).status == on) {
    if ($nick == %mimic.person) {
      describe $chan $1-
    }
  }
}

on *:NICK: {
  if ($nick == %mimic.person) {
    .set %mimic.person $newnick
  }
}

menu channel,nicklist,query {
  .[-Mimic-]
  ..Mimic Person: { mimic $$1 }
  ..End Mimic: { mimic.off }
}

that will make it mimic the person in every channel your in with them