okay, okay i see you are going to force me to be serious:
a mystical experience to me would be one in which the experiencer perceives, what to them, appears to be a supernatural event, that is to say something for which the experiencer has no logical/rational/'scientific' explanation, but which the experiencer cannot dismiss as having been hallucinatory in nature.
this would run the gamut from seeing objects flying across a room to apparent demonic possession to encounters with angelic beings to near death and out of body experiences. any of those experiences can be imbued with a spiritual meaning for the experiencer (or not).