3 boy and 5 girl

Work is usually lonely when my boss is gone. I have the whole Chapel mostly to myself. Occasionally some chaplains will come in, or some maintenance people. One such old maintenance man comes in once a week to water our plants. It's not really his job, but apparently we don't take good enough care of the plants, so he's kind of adopted them. Today he walked in, watered the plants, talked to me a little in his great accent, and left. Then he walked in again, as if he forgot something he wanted to tell me. He said:

The other day, my wife left the door open, and all these flies come in. I get so angry, I start killing them. So then, I kill eight flies. And I lay them all on my wife newspaper, in a little row.
When she sees them, I say, "I kill these flies that you let in. 3 boy and 5 girl."
And she say, "How can you tell?"
I say, "Well, 3 of them were flying in my tequila glass."
She say, "And the other 5?"
"Mirrors."

Then he left again.