AKA the green maggot. Once a soldier is in one of these, it can be hard to extract him. After a year or two, the average army sleeping bag contains enough of a soldier's DNA to construct an exact 1/6th scale replica, just like 'Mini Me'.
Known as a Farter/Gonk Bag in the ADF.
Can be found to often contain a well used wank sock
See also Barnes-Wallis