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

keep one’s pecker up • put someone’s pecker up
keep one’s pecker up —(UK coll.) keep one’s spirits up: Charles
could not eat, in spite of the rough kindness of one of the
warders, who adjured him to keep his pecker up.
put someone’s pecker up—(coll.) make smb. angry; put a per-
son out of temper: He thinks he can do what he likes with
me. I am not quite sure about that, if he puts up my pecker.
keep one’s shirt on • lose one’s shirt
keep one’s shirt on —(coll.) remain calm; keep one’s temper
(also: hold one’s shirt): I told him to keep his shirt on, no matter
what the provocation.
lose one’s shirt—lose all one’s money (as a result of gambling,
etc.): Everybody knows that John lost his shirt when that busi-
ness he had invested in failed.
keep oneself dark • keep someone in the dark
keep oneself dark —be characterized by inconspicuous behav-
ior; keep out of the public eye: He hid himself … kept himself
dark, as he says, out of the way and out of the trial.
keep someone in the dark —keep a person in ignorance about
smth.: He is prepared to do things his own way and to keep
everyone else in the dark as to what is happening.
Note: 
The expression does not correlate in meaning with the
phrase be dark on someone—(Austral. sl.) be angry or annoyed
with a person: Dad’s going to be dark on me for getting home
so late.
keep someone at bay • keep the wolf at bay
keep someone at bay —(also: hold someone at bay) maintain a
safe distance from smb.; prevent a person from acting: These
people come from sick, evil families and we good Americans
are trying to keep them at bay.
keep the wolf at bay —manage to make enough money to
avoid going hungry or falling heavily into debt: An engineer
can just about always survive by computer programming, so
we kept the wolf at bay when I took a job in Houston.