Quote by JeanPaul Sartre, No Exit, 1945
So this is hell. I'd never have believed it. You remember all we were told about the torture-chambers, the fire and brimstone, the burning marl. Old wives' tales!There's no need for red-hot pokers. HELL IS--OTHER PEOPLE!(spoken by character Garcin) http://www.nyu.edu/classes/keefer/hell/sart.html
Summary
In this quote from Jean-Paul Sartre's play "No Exit," Garcin expresses his disbelief upon discovering that the traditional concept of hell as a physical place of torment is nothing compared to the torment he finds in the presence of other people. Sartre suggests that the true essence of hell lies in the constant scrutinizing and judgment from others, where individuals are unable to escape their own self-consciousness and the fear of being constantly observed by their peers. Thus, "hell is other people" implies that the inescapable scrutiny and condemnation from others can create a personal hellish experience.