Trying to figure out why my teleportation code was being triggered twice when I was streaming earlier today. I built a test scene and observed the following (simplified):

func _on_body_entered(body):
	print("entered")
	teleport()
 
func _on_body_exited(body):
	print("exited")
 
func teleport():
	print("reparent")
	self.reparent( ... )
	print("global position")
	self.global_position = ...

This results in the following output:

entered
reparent
exited
entered
global position
reparent
global position
exited

Since reparent appears to result in a body entered and body exited callback, this ends up triggering the teleport code again.