This quote is a way of saying that it takes strength to be tough, not just bravado or bullying. By suggesting that growing a vagina is a way to be tough, the speaker is implying that feminine traits, such as courage and resilience, are tougher than traditionally “masculine” traits. It is also suggesting that physical toughness does not equal strength of character. Essentially, the speaker is using the phrase “grow some balls” sarcastically to criticize the idea that displaying masculine behavior is a sign of strength or toughness.