Libil /ˈlɪbɪl/

Basa Walikan is a way to to encode your message (usually written in Javanese), similar to Caesar Cipher. But Instead of using Latin alphabet as the subtitution, It uses Javanese Script to form the rule. It only shift the consonants, not vocal. The usage of this kind of 'encoded' language is profound among people in Yogyakarta. It's even used by famous local brand. This Page explains the rules clearly. There's another style of Bahasa Walikan in Malang. The rule for Malang is a lot more simpler, it just reverse the whole word. But there's a gotcha here, for digraph like ng and ny you'd need to be careful not to flip that.