Language / English slang but potential Polish slang too! [5]

Last night, I was talking with my g/f on the telephone and she asked me what the English word 'Yep' meant (i.e. slang for 'Yes').

Then she told me that the english pronounciation of 'yep' is slang in Polish (pronounced 'jep') but didn't say what it meant!

Does anyone know what this is?