once when a dentist used N2O on me to extract four teeth in preparation for braces..

What a *horrible* experience.

"Set and setting describes the context for psychoactive and particularly psychedelic drug experiences: one's mindset and the setting in which the user has the experience. This is especially relevant for psychedelic or hallucinogenic experiences; the term was coined by Timothy Leary. The set is the mental state a person brings to the experience, like thoughts, mood or expectations. The setting refers to the physical or social environment. Social support networks have shown to be particularly important in the outcome of the psychedelic experience [1]. They are able to control or guide the course of the experience, both consciously and subconsciously. Stress, fear, or a disagreeable environment, may result in an unpleasant experience (bad trip). Conversely, a relaxed, curious person in a warm, comfortable and safe place is more likely to have a pleasant experience."