Bonus points if it’s usually misused/misunderstood by the people who say it
“They need to pull themselves up by their bootstraps!” Apparently, the quote originates from like a late 1800s textbook or something, and it was a logic problem: “Why cannot a man pull himself up by his own bootstraps?” It’s not possible, 'cause physics.
It could have been a reference to the story of Baron Munchausen from 1860 where the baron and his horse got stuck in a swamp and he lifted himself and his horse by pulling on his pigtail.
Here’s an image of it. https://blogs.loc.gov/international-collections/?attachment_id=3246