Golf is a NOUN, not a verb. Any dictionary that says it's a verb is wrong. Golf is a game that is played. Play is the verb and golf is the object of that verb. Just like these other games: tennis, soccer, basketball, volleyball, polo, bridge, and others which I haven't thought of. One doesn't say I'm tennising, or I'm basketballing, or poloing. These are nouns and therefore can't be gerunds. On the other hand, ski and swim and look and think are verbs. One can say: "I like to ski" or "I skied yesterday" or "Skiing is fun". All these sentences are correct because ski is a VERB!