there isnt normally a totally random text everytime, its one of a set
you could try something like this
on *:text:!8ball:#channel:{ notice $nick Usage for 8ball is !8ball <your question> }
on *:text:!8ball *:#channel { describe $chan answers $nick with a $read(!8ball.txt) }
Then in !8ball.txt file just have lines that it might reply, ie:
yes
no
not today
not maybe another time
not maybe not
not mostly
mostly not
mostly
rarely
sometimes
always
never
This is the simplest i could think of.