What happens if you drop a spider or ant from a 20 story building?

My bet is that gravity pulls them down to the ground.

If you mean what would happen to the ant or spider, i'd say probably not too much as far as physical harm. Being very light and with a lot of legs that cause drag, a spider or ant's terminal velocity (the speed at which a falling object stops accelerating because the forces of gravity and air friction are equal) is probably pretty slow, not to mention they're both built pretty tough. I'd guess the dropped ant/spider would be dazed and disoriencted, but not harmed.

It would depend on how big it was. Dropping a big heavy spider like a tarantula that far would kill it. A small ant could survive a drop from any height. Their terminal velocity is so low that it would not hurt them.

hopefully the wind will catch it but otherwise nothing much. air pressure should slow it down in a perfect environment. Unless this is a large ant or there is no pressure in which case it'll die. Same as a person jumping off.

They fall on peoples head like you and inject poison in their skulls, to make them NOT ask stupid questions :)

he catches the side and crawls back up

why would anyone do that