Backslang???

OK, so people I know have a habit of speaking backslang around me and I can’t speak it, so I don’t know what they are saying. There are two rules and I know one so I get bits and pieces of conversations such as hearing my name mentioned but they won’t tell me what its about or how to speak it. Like, I’m Jess so its said J-vig-ess or like Nikki would be N-vig-ikki and whatnot. So does anyone know the second rule so I can finally understand?