dead people do not "groan" it is trapped air escaping from their trachea making it sound like a groan. they dont "fart" either most gas in the body is located in the stomach which is bacteria reproducing from the host who has become deceased.
take it from someone who worked at a funeral home.
well, taking it from someone who has seen it happen personally, when rolling a deceased person from the back onto their side they FARTED... (Person rolling them over got a face full of fart gas, jumped up, ran outside and vomitted) Very Very funny.
On of the major dictionarys ( Oxford i think??) describes a fart as "A small explosion between the legs".
If it looks like a duck, quacks like a duck and has feathers, its a duck...
Even squashed frogs have feelings. (Sticky and wet.)
Dead people sure do fart. It is very rare to hear the "groan" but noise can be heard sometimes when a body is moved and air escapes. BTW, hair and fingernails do not grow after death...that is an old wive's tale. ~~Nobtis