Answer:
You get many of me, but never enough. After the last one, your life soon will snuff. You may have one of me but one day a year, When the last one is gone, your life disappears.
Hold these between your knees if you want to set a Cuban beat.
People are hired to get rid of me. I'm often hiding under your bed. In time I'll always return you see. Bite me and you're surely dead.
My first master has four legs, my second master has two. My first I serve in life, my second I serve in death. Tough I am, yet soft beside. Against ladies cheeks I often reside.
Black we are and much admired. Many seek us if they are tired. We tire the horse, and comfort man, and turn White when we've fulfilled your plan.