We see the stars as they appear in space, and the camera
flies through, showing the stars flying across our vision, as the announcer
says: “In space, no-one can hear you fart.” Then the camera cuts to inside a
small space station, as one astronaut farts audibly, and all the other
astronauts notice and then gag in revulsion from the smell, leading them to open the airlock
and they all get sucked out into space. Then the announcer says: “Um, on second
thought, maybe they can hear and
smell it. So maybe you need Gas-X.”
(This is a joke on that famous Alien ad mine: “In space,
no-one can hear you scream.”)
