Montreal's Mainline Theatre has brought “Gratitude” by Oren Safdie to New York's Urban Stages, and it is quite a strong premier for the show. Set in a private school in Canada in a disused locker room, the play explores teen sexuality (quite vividly), gender and consent. Throw in the clash between Canadian and the more traditional societies from whence some of its immigrants have come, and you have a play that is tense and uncomfortable to watch in places. The discomfort is deliberate. Indeed, it could be the whole point for some. “Gratitude” opens up a lot of topics that make