Disinhibition is an odd word. Inhibition is "being inhibited", or being reluctant to do something, for whatever reason. Disinhibition is being less reluctant.
- Alcohol is the best known drug for disinhibition, where "normal" people who would never think of dancing on tables or making a pass at the boss' wife do so "under the influence".
This is also an important concept in the use of anti-depressant medications, as a rare person will start to feel better, and then commit suicide.