Dummy - proof

Hi,
I heard this phrase in " Fast and Furious 6" movie.
in that scene one man ( his name was Roman) was playing with a spear bowler machine ( the one , that using for hunting whale or...) and the man (his name was Tej) who made that ( machine) ,when see that man is playing with his machine , he comes forward and says that : " Hey! don't touch that. that's nothing to play with , man." Roman: " what's the problem? " Tej :" that's high-tensile titanium cable." Roman: " what does that mean?" Tej: " that's what they use to anchor building and hold up bridges, stuff you know nothing about! . see i reversed the gears torqued the motor and added this tank to the back" Roman: " that makes it even sweeter."Tej: " it does.(now Roman take machine from Tej with force). Tej: " it's not dummy-proof"

I will appreciate your help if you tell me the meaning of "dummy-proof"?
thank you all

"Dummy-proof" = "designed so that a dummy [unintelligent or ignorant person] cannot mess it up"

So saying "it's not dummy proof" means "it's vulnerable to being messed up / broken by someone stupid." Tej is saying "don't touch that cable, because you don't know enough about it to prevent messing it up!" (or, less generously, "because you're stupid and might mess it up").

This is a similar construction to "child-proof medicine bottles" (which have a difficult mechanism to open so that children cannot ingest dangerous pills).