Here's my suggestion. This will read a random line every 5 minutes, and as long as that line hasn't been said more than 10 times in 2 hours, it will be sent to the channel.
This also presumes that the random sayings are in a text file called rand_saying.txt
Code:
on me:*:join:#:{
  .timer 0 300 rand_saying $chan
}
alias -l rand_saying {
  :rand_saying
  var %rand_saying = $r(1,$lines(rand_saying.txt))
  inc -u7200 $+(%,rand_saying,%rand_saying)
  if $($+(%,rand_saying,%rand_saying),2) > 10 {
    goto rand_saying
  }
  else {
    .msg $1 $read(rand_saying.txt,%rand_saying)
  }
}