Does he respond to peer pressure/ care about what others think? You could explain why behavior is not appropriate and how it makes other people feel including you- that it may frighten other people to watch it or is unsanitary - and talk with him about something that would be more acceptable like chewing gum, sucking thumb or…. Sometimes I do the behavior to show him what it looks like or you could put him in front of a mirror and explain that, although it’s pretty fun for him to watch it, to others watching him, it looks gross and ask if he can find another activity that does not have to do with his saliva. The gum he can pull out of his mouth and has same drooping effect.

Great idea, yes we've tried it, but it has been really hard enforcing it. The good news is that it is happening more consistently during his leisure time, so trying to add as much structure to his day as possible. Thanks again!

So crazy idea, but have you tried giving him a time when he can do it by himself that would be appropriate like when he’s getting ready in the morning and went to before he goes to bed