Keeping up with the Joneses.
Jones is one of the most usual surnames in Great Britain.  If you have to copy your neighbours by acquiring new goods, making improvements to your home and garden and being seen with the right people in the right places, you are keeping up with the Joneses.

Murphy’s law means that anything which can happen will happen.  Murphy is one of the most usual Irish surnames.

Plain Jane and no nonsense.
Jane has been a popular name and various spellings have been used, Jayne for example.  Plain tends to be the opposite of attractive when applied to people. The expression means ordinary, although there are sure to have been some remarkable people with the name!

Not on your Nelly.
The Oxford Dictionary of Phrase, Saying and Quotation has the derivation of this as rhyming slang, where Nelly Duff means puff or breath of life, so Not on your Nelly means the same as not on your life or not likely.  The name Nelly is a pet name for Helen.

Every Tom, Dick and Harry…
…means everyone.  These have often been popular diminutive names, from Thomas, Richard and Henry.

A whiskery Sam
is a man who is not clean-shaven.  Sam is another popular name being short for Samuel.

Hobson’s choice
is no choice at all.  Tobias Hobson who lived in Cambridge according to Brewer hired out horses, but always the one he had placed nearest the stable door so that all the horses were exercised equally.

I know my name is mud down there.
Name can also mean reputation.  A rather outspoken person in my family used to say this. She  thought that some people she was working with to raise funds did not think much of her, but then she was upset when a friend started calling her Mrs. Mud!

An Adam’s apple
is a part of the anatomy of the throat, which appears as a lump on men’s necks.  The name arose from the story of Adam and Eve in the Garden of Eden.   It can be found in Genesis Chapter 3.

As old as Methuselah
means very old.  Methuselah was the oldest man in the Bible.  Although Methuselah was the oldest man, his father Enoch, did not die, but God took him away.  Genesis Chapter 5 verses 21 to 27.