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! Killing any?" She asked.
"Yep, 3 males , 2 Females," he replied.
"How can you tell them apart?"
He responded, "3 were on a beer can, 2 were on the phone.