His name is Murray Cook, but many of you know him as the red Wiggle. And Thursday he plays his last gigs with the Wiggles in Boston. At the end of the year, the original lineup of the Wiggles will disband, and Cook will take on a behind-the-scenes role with the group. “For the first few months, I’m going to take it a bit easy,” he told us just before his trip to Boston. Cook, who cofounded the Australian children’s group in 1991, said that while he can’t really distinguish between audiences in most places, Americans tend to be loudest, especially in cities. That means Boston is rowdy. “Louder and more demonstrative. It’s not the kids, it’s the adults.” Asked what tune he’ll miss singing most, Cook said the crowd pleaser, “Hot Potato.” No, he’s not sick of it yet. The Wiggles play the Orpheum at 2:30 and 6:30 p.m.