bank shot
US /ˈbæŋk ˌʃɑːt/
UK /ˈbæŋk ˌʃɑːt/

1.
a shot in basketball that bounces off the backboard before going into the basket
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He scored with a perfect bank shot from the baseline.
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Practice your bank shots to improve your accuracy.
2.
an action or plan that is intended to achieve a desired result indirectly or by taking advantage of an unexpected opportunity
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His clever negotiation was a real bank shot, getting them to agree to terms they initially rejected.
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The company's new marketing strategy was a bank shot, unexpectedly boosting sales through social media.