What's the origin of "and sh*t"

I'm referring specifically to phrases like, "kissing and shit" or "baseball and shit". Sometimes it is contracted: "n'shit".

"And stuff" has been used in this way since the late 17th century, according to Green's Dictionary of Slang.

The OED has this definition:

Worthless ideas, discourse, or writing; nonsense, rubbish. Often coupled with nonsense (chiefly stuff and nonsense, †nonsense and stuff)

with attestations from the 16th century, followed by this:

phr. —— and stuff, and such-like useless or uninteresting matters. colloq

with attestations starting at the end of the 17th century.

For "and shit", Green's has this:

[1960s+] (orig. US black) a general abstract term, usu. thrown into the end of a sentence, similar to you know phr.

(Two earlier uses are also relevant here to see the sense development: "any inferior, rubbishy, shoddy or pretentious thing" from the 1920s, and "any thing (material or otherwise), irrespective of its actual quality, ‘stuff’" from the 1930s.)

The OED's definition is:

orig. U.S. and shit: and so on; and similar stuff. Also used simply for emphasis

with attestations starting in 1965.

Thus, it seems certain that "and stuff" is the earlier expression, and "and shit" is simply a cruder synonym that has been introduced. Of course, with the history forgotten, "and stuff" may now be perceived (and used) as a euphemism for "and shit".