Mr. Plopper is everyone's friend, but who is he and where does he go? In the book, "Mr. Plopper", we learn who Mr. Plopper is, where he goes, and why he goes there.... every day. As we learn in the first two stanzas of the book, "Who is Mr. Plopper? In fact you will see, Mr. Plopper's the guy you should daily set free. Mr. Plopper's the guy who you feel in your gut. When he's ready to leave you can't keep your butt shut "