Charlie Sheen -- Chuck Lorre Was Stupid to Diss Me ... Watch Your Back Motherf***er

Charlie Sheen is blasting Chuck Lorre for the "Two and a Half Men" finale with the most thinly veiled threat ever, saying ... "You must feel safe where you live!"

Sheen was out at an L.A. mall with some pals (including Darius McCrary) when he was asked about the way Lorre killed him off in the last episode -- falling piano, if you missed it -- and Charlie went into classic warlock mode.

Just a taste -- "To be that stupid ... in my face, really? You must feel safe motherf***er!"

Watch the video ... there's much more, and even if Sheen plays the "it was a joke" card -- Lorre can't be laughing.

Must-See: McCrary's reaction to Charlie's verbal attack. Classic.