Secrets
as quiet as a mouse
silent or very quet
to change your tune
to lie to avoid hurting someone's feelings
to have something up your sleeve
something ready, but not yet common knowledge
grin and bear it
accept a bad situation without complaining
behind closed doors
out of sight, in secret, without public knowledge
to hit the right note
is appropriate or the right thing to say
to lie through your teeth
to tell a blatant lie
off-the-cuff
unprepared and spontaneous, e.g. a comment
to put your foot in your mouth
somebody cracks
to break under pressure and reveal everything you know
to put somebody in the picture
to explain the facts about a situation
to pull someone's leg
to jokingly lie to someone
something is a feather in your cap
an achievement to be proud of
to pull your socks up
working harder
an informal request to keep sth a secret
to jazz something up
to make something brighter, more colorful or more exciting
to take somebody for a ride
to deceive or cheat somebody
at the drop of a hat
immediately, without thinking too much about it
a close shave
a situation where something nearly happened
dark horse
a less well-known competitor or candidate who succeeds to an unexpectedly high level
to drum up
to achieve sth by making an effort
above board
honest, open or legal
a clever clogs
a person who likes to show how intelligent they are
to go Dutch
to split your expenses, e.g. on a date