He didn't.
I can only assume that you're thinking of Vincent Van Gogh who, famously, was said to have cut off his own ear and give it (as a gift!?!) to his girlfriend.
Apparently, he didn't either. New evidence has recently surfaced that Van Gogh lost (part of) his ear in an absinthe-fuelled fencing fight with friend and fellow artist Paul Gauguin in a row outside a brothel. Vincent then apparently wrapped it in cloth and handed it to a prostitute, called Rachel. I'm sure she was thrilled. According to reports, afterwards both men agreed to tell the police the popular self-harm story to protect Gauguin.
I can only assume that you're thinking of Vincent Van Gogh who, famously, was said to have cut off his own ear and give it (as a gift!?!) to his girlfriend.
Apparently, he didn't either. New evidence has recently surfaced that Van Gogh lost (part of) his ear in an absinthe-fuelled fencing fight with friend and fellow artist Paul Gauguin in a row outside a brothel. Vincent then apparently wrapped it in cloth and handed it to a prostitute, called Rachel. I'm sure she was thrilled. According to reports, afterwards both men agreed to tell the police the popular self-harm story to protect Gauguin.