strike pay dirt
To discover or happen upon something very, particularly, or abundantly valuable or useful, especially after a long or arduous search. I was combing through books in the library for hours, trying to find material for my thesis, when finally I struck pay dirt with an old collection of literary criticisms from the 1970s. I loved to search through my grandfather's attic when I was a kid, convinced that someday I would strike pay dirt.
strike whilst the iron is hot
To make most of an opportunity or favourable conditions while one has the chance to do so. (A less common variant of "strike while the iron is hot.") Primarily heard in UK. This sounds like a pretty amazing deal they're offering. If I were you, I'd strike whilst the iron is hot. I deliberated too long before accepting the job offer, and now they've given it to someone else. I should have struck whilst the iron was hot.
strike (someone) dumb
To render someone speechless, as due to a great surprise or shock. My father's sudden resignation from the company struck each of us dumb.
be struck dumb
To be rendered speechless or dumbfounded, as due to a great surprise or shock. We were all struck dumb by my father's announcement that he was resigning from the company.
strike oil
1. To access stores of oil while drilling into the ground. Stop drilling, we've struck oil!
2. To achieve success in some area, often financially. A: "We sure struck oil when we recorded that song." B: "I know, it's become a huge hit and will pay us a ton in royalties."
strike (one's) flag
To lower the flag on a ship in a show of surrender. Captain, they've struck their flag! We've won!
strike sail
1. To lower the sail on a ship in a show of surrender, salute, or during high winds. Captain, they've struck sail! We've won! Those are gale force winds. Strike sail or we're done for!
2. By extension, to admit that one has been bested. You need to strike sail. You've clearly been beaten and need to move on.