在你眼里我连小三狗都不如
[zài nĭ yăn lĭ wŏ lián xiăo sān gŏu dōu bù rú]
This username implies that the person feels extremely devalued or unappreciated by someone else, to the point where they feel even inferior to something considered low or insignificant like a 'third party (cheating)' or a dog. It's a very self-deprecating and emotional name.