莫欺少年木媳妇
[mò qī shăo nián mù xí fù]
The name conveys 'do not deceive/bully the youth/young man', but '木 (mù)' could mean simple/natural/unemotional here while '媳妇' typically refers to wife. So this username could be seen expressing the idea that one should not wrong someone who appears simple, naive, or not easily showing emotions - especially in a more youthful context. A nuance may suggest defending one's vulnerability or simplicity.