favorite phrase?

I have listened the phrase "doesn't matter" over and over since he came to us. I wonder if the phrase is his line. Or is the phrase used very often in daily life? For example, when I asked to him "What do you want to eat for dinner?", he answered "doesn't matter". Or when I asked about the order of pluging adapters, he answered "doesn't matter". I knew that the phrase "doesn't matter" was convenient phrase. Also, he uses the word "try" when he encourage someone to eat. I can learn a lot from talking with him.