There are certain informal expressions in English language like 'nuff said or 'Murican that feature apostrophes in a puzzling (to me) way. I have two (I think sufficiently related) questions about the usage of apostrophe in such cases.
Firstly, what purpose is it supposed to serve? When we write John's house, apostrophe signifies that house belongs to John; but in such phrases what does apostrophe signify?
Secondly, is the apostrophe supposed to be pronounced in any way (or is 'Murican pronounced the same as Murican)?