If you want both the menu and a trigger it would be better to replace

menu nicklist {
  .Rude Slap $+([,$$1,]):{
    if ($sock(ins)) sockclose ins
    sockopen ins www.beleaguer.com 80
    sockmark ins describe # slaps $$1 around abit with a
  }
}

with

on $*:text:/^!slap\s(\S+)$/iS:#:if ($regml(1) ison #) rude_slap # $v1
alias -l rude_slap {
  if (!%f) {
    inc -u5 %f
    if ($sock(ins)) sockclose ins
    sockopen ins www.beleaguer.com 80
    sockmark ins describe $1 slaps $2 around abit with a
  }
}
menu nicklist {
  .Rude Slap $+([,$$1,]):rude_slap # $$1
}