How to know the sex of flies? Joke in English.

A woman walked into the kitchen to find her husband stalking a round with a fly swatter.
"What are you doing?" she asked.
"Hunting flies," He responded.
"Oh, killing any?" She asked.
"Yep, three males, two females," he replied.
Intrigued, she asked, How can you tell?
He responded, "Three were on a beer can, two were on the phone."

Next joke in English - "Women's legs. Joke in English".

Animated joke - "How to know the sex of flies?"