Sleep like what?

Last night as I went into the kids room to lay down Abbi in her bed I noticed Simeon unzipping his pj's. After I layed her down, I went to Simeon and zipped up his pj's and told him that they should stay zipped up so he would be warm. He then unzipped them again saying that he needed it down so he could sleep with his belly button. I laughed and zipped up his pj's again. I then explained that his belly button was always with him whether he could see it or not. He then unzipped it again and said he needed to sleep with his belly button. So I asked why he needed to sleep with his belly button. He told me that he wanted "to sleep like papa because papa sleeps with his belly button. Papa doesn't wear a shirt to bed". I then explained that papa only does that during the summer time when it is really warm outside. So he looked up at me and asked, "When it really warm outside then I not sleep with my shirt on too like papa, OK?"