Their drop shot bounces on your side and spins back over. Can you go after it?

Reach over and play it, without touching the net. A ball that bounces on your side and spins back over is still yours. Reach over, touch nothing. Normally you may not strike the ball until it has crossed the net to your side. The one exception is exactly this: the ball has already bounced on your side, and spin or wind has carried it back over the net. You may reach across to play it, as long as you do not touch the net, the posts or the ground on their side, and the ball has not bounced on their court. It is rare, it usually happens on very heavily sliced drop shots, and it is worth knowing before it happens to you.

It is playable, and rare, and one of the best points you will ever win.

Just know it exists. If the ball comes back over, you are allowed to go and get it.

This is also why a very heavily sliced drop can be a bad idea against a fast pair: a ball that spins back offers them a free shot with the whole court open.

A ball that bounces on a player's side and returns over the net on its own may be played by reaching over the net, provided the player does not touch the net, the posts or the opponents' court.