It was all tears and laughter as the cast of U’s “Les Miserables” gathered for a celebratory Sunday-night dinner at Porter House New York.“Tom, you had no business two months after winning an Oscar of doing a movie like this. You’re meant to take an easy one,” Hugh Jackman teased in his opening remarks. Tom Hooper explained how he just finished last edits of the film at 2 a.m. on Thanksgiving Day. “That last month or two I had to — I mean, I literally cut my sleep down two or three hours, which I’ve never actually done to that extent, but it’s such a mammoth film,” Hooper said. “I wanted to get everything as right as I could to bring it here to the world.” “But tonight is a special night,” Jackman continued. “And I am going to sing one song.” As the crowd cheered and applauded, a woman in the aud squealed, “Oh my God!” Jackman then introduced co-star Amanda Seyfried, whose birthday was Monday, and sat her on a chair so he could croon “Happy Birthday.” “I once gave Barbara Walters a lap dance and I promised her I would never do it again. But seeing as she’s not here tonight,” Jackman said as Seyfried took a seat. U screened the film earlier in the evening at AMC Loews Lincoln Center.