Four!

Three men were on the first tee box waiting for the group in front of them to clear so that they could tee off. A fellow walked up and handed one of them a business card that said, "I cannot speak. Would you mind if I joined your threesome?"

The reader thought briefly, handed the card back, shook his head and said in his rudest, most unfriendly manner, "No way!"

By this time the fairway was clear and the three men in line hit their tee shots. The first two then hit into the green. Just as the third, the man who had been so rude back on the tee, was about to start his swing, a golf ball came screaming off of tee behind him and nailed him right in the middle of his back.

Enraged and in pain, he angrily turned to look back at the tee box, and there stood our mute friend...smiling...holding up 4 fingers...