I realized that zerg have the unique ability to build an unlimited number of units. As long as those units are overlords. So what you do is this: Get a large army of hydralisks together, fully upgraded ect. Get about 80 of them. Load all of them into some overlords, and hotkey those overlords. Now, build MASS amounts of overlords! About 50 at the very least. Depends on how much lag you can handle. Now you can send the empty overlords slightly ahead and around the real ones, they should take 90% of the attacks from the opponents anti air force. Get as far into his base as you dare (Getting all the way to his nexus/command centre will do no good without troops) and drop your horde of hydralisks in the middle of it all. If you have air troops as well, you can use the drop to put them right near his anti air, and clear it out so you can bring in some guardians/mutas.

CreepColony's Opinion: Try to build your overlords ahead of time.