特纯叔优质男源自1999
[tè chún shū yōu zhì nán yuán zì 1999]
It's a self-deprecating or joking way to call oneself 'a very pure uncle' with an added specification of 'born in 1999'. It shows humor and modesty while subtly advertising themselves as a high-quality gentleman, likely trying to portray a friendly yet mature and responsible image