I like to ruin pedestrians' rainy nights.
How do you ruin their rainy nights?
I'm laugh at them and say "Ha ha, it's raining and you look like a drowned rat."
You should not go about ruining other people's nights by making mean jokes. Making fun of others is not going to fix any underlying issues that cause you to be insecure. All it is going to do is make you look like a mean person.
But it's fun to annoy them.
It might be fun for you, but they're already getting rained on, so there's no reason to taunt them even more. If someone is having a bad time, you shouldn't go out of your way to make them feel worse.