How people usually cause it:
1- Load some kind of mod that adds custom glasses
2- Select any of the custom glasses on your profile and save it.
3- Exit the game
4- Load the game without addons
5- Join a vanila server without addons
6- Profit.... all the server will get a annoying message, "no entry 'config.bin/cfgGlasses.NAME_OF_YOUR_CUSTOM_GLASSES'"
Alternate metod:
Instead you can also just eddit your profile with a text editor and set a random name on the glasses field.