Forums Scripts & Popups on *:text: script (random option)

i want to make a script that for example displays the phrase hi (their nickname.)

on *:TEXT:hi:#:{ msg $chan hi $nick $+ . }

but i don't always want it to activate when the person says "hi". How can i make it so it randomly displays the message when the person says "hi"?

Edit: in other words sometimes i want it to activate normally and other times randomly not activate