What's the difference between dark humor and normal humor?

Normal humor is ten babies and one trash can.

Dark humor is one baby and ten trash cans.

Scroll down for explanation.

Ten babies in one trash can; one baby in ten means that the baby was chopped up.

I ask my sister why the Chinese owner brings us free food all the time.

My sister said to me "I love him long time."

At night in the Nunnery, one Nun says to the other Nun, "Where's the candle?" The other Nun says, "Doesn't it!"