who only by moving can balance

And surely Surprisingly Curvaceous Pirate is one of the few bits of historical accuracy. I'd have thought the joke wasn't really around women dressing as men (which was by-and-large the only way most women could become sailors of any sort and hence not intrinsically funny), but that this particular woman was spectacularly bad at disguises and the men equally bad at penetrating such a poor disguise. In reality,most of the disguises were so good the truth was only discovered posthumously.