mrtav ladan

1. colloq. (of someone doing something) without batting an eye; with a straight face
   Slagao me je mrtav ladan. — He lied to me without batting an eye.
   Ona je mrtva ladna rekla da ništa nije videla. — She said with a straight face that she hadn't seen anything.
2. colloq. completely calm; unfazed
   Svi su paničili, a on mrtav ladan. — Everyone was panicking, but he was totally unfazed.
   Ostala je mrtva ladna i pred ispitom. — She stayed completely calm even before the exam.

Both words agree with the subject: mrtav ladan, mrtva ladna, mrtvi ladni.