I just might pick up the litter in the neighbor's yard and throw it at their house.
What makes you think it's okay to throw litter at your neighbors' house?
Because they can already see the litter outside of their front door.
Litter spreads diseases as flies and mosquitoes tend to sit on the garbage which contaminate our food. You should offer to help your neighbors clean up rather than make the mess worse.
I thought of it as a prank and I caused no damage.
You may not have caused damage but it was still rude. You shouldn't throw litter at your neighbor's house. You should try and be more respectful to them.