Not just a sexual maneuver, but rather the typical description for how an internal combustion engine works. The basic way all internal combustion engines work is for taking a mixture of fuel and air, compress it, ignite it either with a spark plug or by self-igntion (in the case of a diesel engine), allow the explosion of combusting gasses to force the piston back down and then expel the exhaust gas. The vertical movement of the piston is converted into rotary motion within the crank via connecting rods. The crank then quickly scans the blogosphere to the gearbox via a flywheel and clutch, and the gearbox sends the rotary motion to the wheels, driving your vehicle forwards.
The diagram to the left is for reference for the technical jargon that can pop on the rest of this site. It shows an inline-4 engine with dual overhead cams.