The very idea of a tank being assigned a sex is, well, rather strange to say the least. However, that is exactly what happened during World War I. It turns out that the British army decided to identify tanks by sex, but it was merely done to distinguish between two types of tanks that had different strengths to one another. In other words, it was not as insane as you may have initially thought.
It turns out that the male tank had cannons installed as their main weapon, whereas the female tank used a heavy machine gun as the primary weapon. Each one could then be employed in various situations, but the gender-specific tank was not something that would last for too long a period of time, as it was then decided that a tank should just be a tank and nothing else.