You could say that Allen Covert has had a unique career for someone who is best-known for starring in the underground cult classic “Grandma’s Boy,” and has otherwise drawn most of his laughs from playing oddball supporting characters in Adam Sandler movies. An inner-circle level friend of Sandler’s ever since their days as roommates at New York University, he has been a key part of Happy Madison’s success in the film world, with 38 acting credits, 21 production credits, eight script credits and even eight of Sandler’s comedic songs partly in this name.