It depends how long the story has to be. If it's a full length novel, make it be in the early 1900s. There's a man, lets say he's around 25-35 years old. Shaggy dark hair, green/brown eyes, big nose, full lips. Let's say that a boy, maybe 9-15 years old, stumbles upon him working in a shed in a forest no building is allowed to be in. The shed is near a stream. The boy tells the man just that, and they get into a fight. Eventually it leads them outside and the man falls into the stream... where he sends up sparks and his eyes go black and he goes still. Horrified, the boy drags him out of the river. Then the boy hears a noise and spins around. He sees an old man, maybe around 50-60 years old, and the man takes one look at the thing that sent out sparks and he gets ANGRY! Aparently the man makes robos, and there's a whole society no one is supposed to know about. The boy gets thrown into a battle between his ansestors, and he has to do SOMETHING to make things right... like give up his body to become the first robot/human hybrid. He's waiting in their lair and escapes, but in the end he has to destroy every single robo and human, because every single one is after him.
Write a science fiction story about a race of people that live only in the electrical grid, and thus 'see' all that humanity is doing whenever the electrical object they are assigned to "monitor' is turned on. After they see what humanity is doing they then decide to commit "suicide ' by shorting out the electrical grid and sending man kind back to the "1800's to teach them a lesson". As a final plot twist have the electrical people save some of themselves by launching a spaceship with solar panels and banks of batteries off into the universe.
Write about a space monkey that goes up into outerspace and finds a banana that is rock hard. He tried to eat it but it wouldnt go through the helmet so he went to the pope that were at the space Station and they ripped off the helmet and the monkeys head automatically expoldes! The end.