It’s all Greek to me is an expression meaning I don’t understand it.  The Greek alphabet is unintelligible to anyone without learning.

As happy as Larry means extremely happy.  Larry is a name as in the children’s radio series Toytown, where Larry the Lamb pronounced his name like a baa.  However Graeme Donald gives the derivation from a dialect word, larry meaning confusion or excitement from larrikin – a corruption of larking  (The Dictionary of Modern Phrase).

Jerry-building is substandard construction.  There was a maritime phrase jury built describing emergency repairs to a ship.  The reference book mentioned above gives a more thorough explanation of possible derivations.

Take the Mickey means tease cruelly.

A lazy Susan is a revolving food-stand on a table.  (It saves work.)  Whoever heard of anyone with the same name as me being lazy?

A lazy Betty is a pull-cord light switch, which may be operated from a bed.  Betty is one of the shortened forms of Elizabeth.  Bessie, Bess, Bet, Beth, Bethie, Liz and Lizzie are other diminutives.  Eliza is a name in its own right.

Uncle Sam is a symbol of America inspired by Samuel Wilson.

John Bull is a typical Englishman.

John Brown features is a song –

John Brown’s body lies a-mouldering in the grave, but his soul goes marching on!

Punch and Judy are two glove puppets who appear in traditional puppet plays in striped booths usually at the seaside.  A Punch and Judy Show includes Punch, who is violent, his wife, Judy, their baby and a dog.  The puppeteer is hidden inside the booth.

Murphy’s law is that anything which can happen will happen.  It is usually blamed when something goes wrong.

Name-dropping is mentioning the names of well-known people of one’s acquaintance in the hope of improving one’s own reputation.

Melchizidek is a name you may not have heard before.  (The “ch” is pronounced “k”.)  His story is to be found in Genesis 14:17-24

Hebrews 6:13-8:13 explains how Melchizidek foreshadowed Christ’s work as High Priest.