I think i got this from bearded blunder on here awhile back.... it should work for you Trader.
<OnTimer type="script" interval="1800">
<out type="self">!autotrigger</out>
</OnTimer>
<command type="random">
<in>!autotrigger</in>
// Add as many output lines as you wish
<out>Where is everybody? come out and play you lurkers?</out>
<out>/me throws water balloons at all the lurkers</out>
<out>somebody say something!!!</out>
</command>
just change the "1800" to a lower number and change the outs to whatever you would like them to
say.