Cacoethes - an urge to do something inadvisable. (OED). (See Words worth espousing for the first appearance of cacoethes in this blog.)
In my blogger profile I note that I am given to bizarre utterances. Coming out with bizarre utterances is just one of many ways in which I seek to build entertainment and enjoyment into an otherwise humdrum day.
For example, last week at the hairdressers, I stated that I had an unusual medical condition. I claimed that my hair follicles had pain receptors, and that from time to time, I might flinch from a minor spasm of pain when the hairdresser combed or cut my hair.
The tension was palpable, and all I had to do was draw a sharp intake of breath from time to time to entertain myself.
Fun, and relatively harmless. However I have to exercise great restraint when visiting the dentist. A cacoethes-driven urge to jump or yelp (to feign pain) while at the dentist could have unfortunate consequences, viz: (a) the dentist might be startled into a rash move and cause me an injury; and/or (b) the dentist might not believe me later if I experienced some genuine pain (c.f. The Boy who cried Wolf).