A dictionary of Confusable Phrases: More Than 10,000 Idioms and Collocations

Note: 
Neither expression correlates in meaning with the phrase
get away with it
— go unpunished for doing smth. wrong: The
law says they can defame you and get away with it if the story
is true. Truth is an almost perfect defense in a libel suit.
get one’s blue • get the blues
get one’s blue —(Oxford and Cambridge) be awarded a blue
cap, scarf, etc. for representing one’s university in athletics:
He will get his blue next term and show that he’s a jolly good
fellow.
get the blues —(coll.) feel sad or depressed (also: have the
blues): His excess energy can be misdirected, especially when
he gets the blues (as we all do sometimes).
See also: come out of the blue / get into a blue.
get one’s feet under the table • put one’s feet up
get one’s feet under the table —get settled in: It will take four
or five months for Greg to get his feet under the table, to
understand the enormous number of complex and tricky issues
he has to master.
put one’s feet up —relax or take a rest: That way I can put
my feet up and not think about Christmas at all until a week
beforehand, when we put up our decorations.
Note: 
The expression does not correlate in meaning with the
phrase have a knees up— have a noisy party usually with danc-
ing: We had a little party for him and some speeches and went
to the pub and had a knees up.
See also: put one’s foot down / put one’s foot to the floor.
get one’s pennyworth • have one’s two penny-
worth
get one’s pennyworth —(UK) have full value for one’s money;
get a sufficient return for one’s trouble, etc.: Mr. Cataway
makes sure he gets his pennyworth of work from those assis-
tants.
have one’s two pennyworth —(UK) add one’s comments or
opinion on the matter: Everyone started to leave, but I was
determined to have my two pennyworth, so I stood up and
banged my papers on the table.