to do something without intending to which spoils a situation for yourself
to do or say something that causes problems for you:
I think you might be shooting yourself in the foot if you don't take his offer.
(informal) to do or say something that will cause you a lot of trouble or harm, especially when you are trying to get an advantage for yourself
to say or do something stupid that causes you trouble
The government seems to have shot itself in the foot over this issue.
to damage one's own cause inadvertently
transitive. figurative. to shoot oneself in the foot and variants: to cause oneself difficulty or harm inadvertently; to make one's own situation worse.
In quot. 1959, as part of an extended metaphor.
1959 W. Howells Mankind in Making vi. 97 Certain common useful phrases can be dangerous... Like guns, they will do the right thing in the right hands, but they are loaded, and ordinary citizens without Ph.D.'s are not the only ones who have accidents with them. Many a specialist has shot himself in the foot when he thought he was only cleaning a paragraph.
1976 Aviation Week (Nexis) 5 Apr. 9 Why we seem to insist on shooting ourself in the foot over this issue, I'll never know.
1980 Time 21 Jan. 22 Said Morton Sosland..of the grain embargo: ‘America has just shot itself in the foot.’
1989 Nursing Times 29 Nov. 22/2 Once again ministers have shot themselves in their collective feet by their obsessive desire to privatise everything.
1991 A. Campbell Sidewinder i. 1 Sidewinder is a demon of a fairly high order—although from his ludicrous propensity to shoot himself in the foot you may find that hard to believe.
2001 AXM Aug. 124/2 I did gain a few Brownie points when I told her I'm a journalist... But I proceeded to shoot myself in the foot by informing her that it doesn't pay anything more than chump change.