Yes, just hold up your hand and he will high five you if he wants to. Don’t force it so to speak
Aw :^( I just did Ghostbusters for the 11th(?) time last night; around my 7th or so last week, he initiated a fist-bump with me, and I assumed it was because he recognized me. Last night, he waved but also pointed at me, and I can’t tell if that was just because of his routine or if he did actually notice I was back. :^(
On that note, I always love to mouth along with, “We came, we saw, we kicked its ass!” not only because the line is fun, but because it’s just so antithetical to anything that a scare could be and its silly. It’s not even startling. The fist-bump was when I think he noticed me participating in the line with him, so maybe that’s a way to prompt him to engage?
Finally, as far as I’ve experienced, Cast B Venkman is the one doing the high-fives. Cast A Venkman, observably and from the opinion of the scareactor whose boo hole is very close to his, tends to hit his trigger constantly, which sort of messes up the surprise. I’ve mouthed along but have yet to interact with that one. Cast B Venkman, or “my Cast B boy,” is all smiles, all the time.