Good old amusement park never fails.
If you want something a bit more daring and fun, and you've proceeded to the part of the relationship where you're having sex, go to a golf course at 2 in the morning (or whenever the automatic sprinklers turn on around where you live,) find a flat spot, and run around in your underwear (or naked) and dance under the sprinklers. It's just like what you did as a kid, but this time you're old enough to make the most of the situation
