不知說謂, 不三不四 - Meaning In Context?
不三不四 is a perfectly acceptable term in Mandarin 

Oxford


  IDIOM
  
  1 指人 shady
  
  交不三不四的朋友 
  
  make friends with dubious characters


>


  2 指言词 neither one thing nor the other
  
  说些不三不四的话 
  
  make frivolous remarks


I think you might be mistaking 不知说谓 for 不知所谓 which 汉语大辞典 defines as:


  不知道该怎么办, 犹言无计可施。


不三不四 is definitely better though!