Total Perspective Vortex ?
Originally created by its inventor Trin Tragula as a way to get back at his wife (who always told him to get a “sense of proportion”), the TPV is now used as a torture and (in effect) killing device on the planet Frogstar B. The prospective victim of the TPV is placed within a small chamber wherein is displayed a model of the entire universe - together with a microscopic dot bearing the legend “you are here”. The sense of perspective thereby conveyed destroys the victim’s mind; it was stated that the TPV is the only known means of crushing a man’s soul.
The only person to survive the TPV is former President of the Galaxy Zaphod Beeblebrox. At the time he was exposed to the TPV, he was inside a computer-generated universe created for his protection by Zarniwoop. Since the entire universe was created for him, the TPV told him, in effect, that he was in fact the single most important person in the universe. This allowed Zaphod to survive the experience, and also did not surprise him in the least.