Fires input to the entity with the ability to make another entity responsible, bypassing the event queue system.
You should only use this function over Entity:Fire if you know what you are doing.
1 string input
The name of the input to fire
2 Entity activator = nil
The entity that caused this input (i.e. the player who pushed a button)
3 Entity caller = nil
The entity that is triggering this input (i.e. the button that was pushed)