A woman gave birth to a boy and a girl at a hospital. Her husband, who has an acute sense of humour, named their children. The woman, a bit worried about what names her husband had given their children, asked him what he named them.
"Well," he said. "Our daughter's name is Sheena."
"Well, that sounds good." exclaimed the wife. "What's our son's name?".
He said, "Hee Kung"

Sheena - She Na. "Na" in Chinese means "female"

Hee Kung - He Kung. "Kung" in Chinese means "male"

Here's an in-depth analysis of another variant of this joke. Hope you get it.

Denise & Denephew

What do you call a woman who is flat-chested even when she is in her 30s?