If you set up a chain of submunitions for a missile with alternating subs having positive and negative turn rates, you can simulate a missile that will track for a moment, then veer of momentairly before tracking again.
adjust timing and rates to taset. It can be spastic for a second before it settles out, or have it curve and turn, taking it's sweet ol' time getting to the target.
I suppose you could also make a missile that only turns every few seconds by having the alternate subs at turn rate 0.
With the right timing, you could probably even have missile make a tight, furious, cartoon-like circle before spining off towards the target.
Fun.