I spent some time working on this yesterday and got nowhere. I approached it in a better way this morning, and I figured it out. Yay.
Start with the letters "H - O." Add two consecutive letters of the alphabet, like "A - B" or "B -C." Then add 2 more consecutive letters of the alphabet, then do this a 3rd time and a 4th time. Then add the letters "N-T." The resulting 12 letters, in order, will spell a familiar two-word phrase. What is the phrase?