"Only Once is Enough" joke

At a resort, a guy walks up to an older fellow who is sitting in the sun, sipping iced tea.

Young guy says, "Hey, how about a round of golf?"

"Nah," the older fellow replies, "tried it once, didn''t like it."

"Well, how about a swim? It''ll be more refreshing that your iced tea there."

"Nah," the older fellow responds, "tried it once, didn''t like it."

"Young guy says, "Well, how about a game of tennis?"

"Naw, tried it once and didn''t like it. But my son will be here soon. He''s usually up for a game or two."

Young guy replies, "Your only child I presume?"