tripper

Noun

• a catch mechanism that acts as a switch
  • the pressure activates the tripper and releases the water
    

• a tourist who is visiting sights of interest

• a walker or runner who trips and almost falls

• (slang) someone who has taken a psychedelic drug and is undergoing hallucinations

Related words

• Synonyms: 
  trip , sightseer , excursionist , rubberneck , stumbler