Monkey Footie Pajamas

footie pajamas
The blanket sleeper (also known by many other synonyms and trade names) such as is a type of especially warm sleeping garment worn primarily during the winter in the United States and Canada. The garment is worn especially by infants and young children.

monkey
A small to medium-sized primate that typically has a long tail, most kinds of which live in trees in tropical countries
any of various long-tailed primates (excluding the prosimians)
(in general use) Any primate
A mischievous person, esp. a child
imp: one who is playfully mischievous
tamper: play around with or alter or falsify, usually secretively or dishonestly; "Someone tampered with the documents on my desk"; "The reporter fiddle with the facts"