By Daniel Bates New series, new hair. Ahead of the Boston Celtics second-round playoff matchup against the defending NBA champion Bucks; Defensive Player of the Year Marcus Smart pulled up sporting green hair. NBA Twitter reacted Smart’s new look on Sunday. “This fit is unbelievable,” replied a Boston fan. “Celtics in five. #BleedGreen.” “Celtics by a million!” tweeted Peter Stringer. “We’re going to another [expletive] planet today,” replied another fan. “THAT’S HARDDDDD,” another user commented in all-caps. “Lets goooo,” said another Celtics fan. “My GOAT. My literal GOAT came to work with t…