I don't know if you were joking about the hammer or referring to a Russian assembly worker who used a hammer to install accelerometers in a rocket into a wrong position which caused it to attempt to fly downwards (no people were injured) [1].
No, unfortunately, I'm not joking. The 737 NG and MAX fuselages were assembled inconsistently and badly for 20+ years. Bear straps and other critical parts were percussively persuaded into place.
[1] https://en.wikipedia.org/wiki/Proton-M#Notable_launch_failur...