Killing Flies

A woman walked into the kitchen to find her Husband stalking around with a fly swatter ... "What are you doing?" She asked. "Hunting Flies" He responded. "Oh! Killed any?" She asked.

"Yep, 3 males, 2 Females," he replied. Intrigued, she asked. "How can you tell them apart?"

He responded, "3 were on a beer can, 2 were on the phone."