To say it in a more formal way with fully proper grammar you would have to change the prefix to include the object nuq. Also, the -pu' makes it perfective, which is fine, but I'm going to go with the simple past. So the question would be nuq Dajatlh? However, nuqjatlh is listed in the Addendum of The Klingon Dictionary as an exclamation meaning, "What did you say?" Since we have not yet taught the grammar for the sentence nuq Dajatlh?, we teach this exclamation near the start.