Why do you think young children need to be aware of perverse sex ideas, or sex ideas at all?
Obviously you have no children. They notice things and ask questions. Your choices are to answer honestly within their understanding, or do like my mom always did when something was uncomfortable (like when I found her b.c. pills behind the candy in a kitchen cabinet): "Never mind." That gives the kid the idea that something is bad/wrong. (I thought she had cancer and was going to die and that's what that medicine was for.)