About the song Let's get it on?

The song is by Marvin Gaye, I was listening this song and the radio host said that someone had offered it to someone else. And when I heard the part that says Let's get it on, the first time I smiled about it, but as the song went on I kept on thinking what this couple looked like and about them getting it on. No I am not sick, it is like someone showing you a picture and telling you not to look at it, I mean come on, so I changed stations. That song is so weird, I don't know, what do you think?