Scabble Should Be on the Honor System

Okay so our whole married life, David and I have been avid board game players. We pretty much take turns at winning or losing. However, there is one game that I have never won, Scrabble. We decided to play it on Monday and I pretty much had the eye of the tiger this time. I was doing really well, I was up by 25 and David had only one turn left. Of course, he scored a 30 point word. I was crushed. Right after the game, David told me one of the words he made wasn't a real word. I checked the dictionary and he was right. Because I hadn't challenge the word, he still won, and of course that word was worth 6 points, which I think is RIDICULOUS! Can you figure out what the word was?? Scrabble should really be on the honor system...