One of Tom Cruise's neighbors got drunk, stumbled onto Tom's Beverly Hills property ... and then got zapped with a Taser for his mistake ... according to cops.

BH PD say the man, Jason Sullivan, drunkenly attempted to scale a fence at the Cruise home around 9PM last night ... and was met by a security guard who opened fire with a Taser.

When police officers arrived they caught Sullivan trying to run away from Cruise's house -- and the guard -- and arrested him for trespassing.

The Taser jolt messed up Sullivan badly enough that paramedics had to take him to a hospital for treatment. Cops say 41-year-old Sullivan actually lives in a home "adjacent" to Tom's ... and, due to "intoxication," may have gotten confused and entered the wrong property.

Tom was not home at the time of the incident.