Screwdriver to screw driver

Ok...try to understand from what you can understand.

Take a screwdriver and screw a screw up the school driver's bus, then unscrew all the screws on the school's bus but with a screw driver but don't unscrew the screws from the school driver's bus as the screws are screwed up by the school's driver. Finally take what's left of the screw and drive it up the driver with a screwdriver then you driver the driver crazy till he's officially screwed.

hahhaa..
so you are SCREWED