Ok I saw this movie a very long time ago when I was super young so this may be a bit vague but it is driving me insane not being able to remember what it was, all I remember is this little boy and girl hiding behind a hedge and spying on their parents who were having some kind of garden party in the boys backyard, the kids kissed at some point? and I think they had found some kind of box in the back yard and were trying to keep it from their parents? I think his parents were rich because I remember they lived in a really nice house. it was in color. I believe it was some kind of horror movie but it may not have been I just remember it creeping me out as a child. Not sure what year it was made but I either saw it late late 90’s or very early 2000’s. I THINK I saw it on tv but im not 100% sure on that.
Could it be Nanny McPhee? http://www.imdb.com/title/tt0396752/
Not a horror movie, but definitely had some creepy parts that could give kids nightmares!