Have you ever pondered the wide variety of creatures on this earth? Everything from dogs and cats (whose antics often produce laughter) to zebras, giraffes, platypuses, and some pretty spectacular (and amusing) sea creatures. I imagine God had fun thinking up ideas for animals. And that's just the animals. There are people who have a knack for humor, and I don't know anyone who doesn't like to laugh. So if we believe God is the creator, and that humans were created in his image, it might follow that God has a sense of humor because we are reflecting this trait.
Laughter is often mentioned in the Bible, and although it never explicity says so, I think Jesus must have laughed. He spent a lot of time hanging out with people, eating and visiting. I can't imagine he was the most somber person at the table. And Ecclesiastes indicates there is a time for everything, including laughter. The proverbs talk of laughter as medicine.
So yes, I think my creator has a sense of humor. I will remember this when I see his created world and hear the laughter of people.