女汉子的前世是萌妹子
[nǚ hàn zi de qián shì shì méng mèi zi]
It portrays a contrast between toughness (female tough individual, or 'nühanzi') and the past cute and innocent self (cute girl or 'meng meizi'). The username could imply that women who now appear strong were once tender or have a side few see.