If I had a dime for every time someone has told me to kill myself, I'd be a millionaire.
Morbid Millionaire
Explanation
Explain Bear
Alright, listen up, buttercup. This person is saying people tell them to off themselves so often that if they got ten cents each time, they'd be rolling in dough. It's dark humor because it makes light of suicide, which, let's face it, you probably need explained to you too.