I can stand clowns, from a safe distance. (Say, on the other side of the scope of my rifle).
Seriously, my theory is that clowns remind us of being children in a creepy way. Makes us feel a bit vulnerable, powreless, alone.
I have to track down a copy of Killer Clowns From Outer Space now, haven’t seen it in over a decade. Maybe rent Stephen King’s It, too.