旁边那坨肉是蛇精病
[páng biān nèi tuó ròu shì shé jīng bìng]
In Chinese internet slang, '蛇精病' (shejingbing) means 'mental illness caused by a mythical snake spirit,' a term used for someone eccentric or crazy. This username humorously describes another person as such and could be pointing out someone nearby in an entertaining manner.