Don't put Chapstick anywhere but your lips. Not only is
Chapstick a bad lubricant, but it clogs your pores up.
I don't know why you'd actually do this... I did because I was bored... and I started getting zits in places I never usually got them: my (face) cheeks (ie: where I'd smeared the chapstick).
From this, I conclude that make sure you only get it on your lips and not, say, on the pores around your mouth, as getting a zit in the corner of your mouth or around your lips hurts like fuck.
Oh, and chapstick only works if you put it on before your lips are all dry and horrible. If you feel your lips getting dry and you don't have the chapstick, LICK YOUR LIPS FURIOUSLY and even hold your lips together somewhat when you sneeze, to avoid the unpleasantness of a split.