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

be on one’s own ground • stand on one’s native
soil
be on one’s own ground —(also: be on home ground) 
1
. be in
the area where one works or lives (with the implication that it
makes a person feel confident and secure): Whenever possible he
liked to make a point of talking to drug users on their own
ground. 2. be competent in a subject because one is thoroughly
familiar with it (with the implication that it makes a person feel
relaxed and comfortable): And where he is on his own ground,
as in the chapters dealing with family life, he exercises his
well-known mastery of observation.
Note:
The expression does not correlate in meaning with the
phrase stand one’s own ground—(also: hold one’s ground)
maintain one’s firm position in an argument, etc: Perry discov-
ered that he could stand his own ground and still be respected.
stand on one’s native soil— be in the land of one’s birth: I am
looking forward to going back to France and standing once
more on my native soil.
be on overtime • be over one’s time
be on overtime —work after the usual working hours: The
men stayed locked up for two hours until their boss agreed
they would repair the faulty central heating immediately —
on overtime.
be over one’s time —(of a woman) be late in menstruating
(the usual implication being that of unwanted pregnancy): “A
fine father and mentor you are. Don’t even realize that she is
over her time,” he cursed himself…
be on pins and needles • have pins and needles
be on pins and needles —(coll.) be in the state of agitated ex-
pectancy: We had been on pins and needles all day long until
we received her telegram.
Note: 
a) The expression does not correlate in meaning with
the phrase be on one’s pins—(coll.) be on one’s feet; be in good
health: When I came home after a number of years, I was glad
that mother was still on her pins.
b) The expression does not correlate in meaning with the phrase