So, tonight my ballet teacher learned about the phrase "shot my wad". She had said it in some ballet context. Discussing the timing of port de bras for balancé or something. And then she said "I don't even know what that means! Is it about slingshots or something?" and as she looked out at thirteen silent faces that were suddenly trying desperately not to make eye-contact realization slowly dawned. "OH MY GOD!"
at least we all had a bit of a giggle.
In reality, though, I am pretty sure the term originated with muzzle-loading muskets (truthfully, I am a bit of a etymology nerd. Did you know "the cat is out of the bag" originated in the navy, and has nothing to do with felines?).
However, it doesn't matter where something actually came from if that isn't the association that most of the people who say it intend.
You really do learn something new every day.