They had a baked bean-eating contest for a front row prize, with four fans gorging out of cans while gaseous sounds groaned out of the PA system. The Bradley Center was at the most a third full, and presumably just to entertain themselves, fans chanted “Ger-ald” at Gerald Wallace, though there isn’t any evidence of the Celtics forward ever picking on Richie Cunningham. But these fans follow the worst team in basketball, and can normally take consolation in the knowledge that the Celtics aren’t much better, though last night the Celts made the most of Rajon Rondo’s scheduled off night. The Celts evened this series of the downtrodden at 2-2 with a 102-86 win over Milwaukee for their fourth victory in the last five games. Jeff Green, who appears to be building some sort of momentum, checked in with 29 points, his best since a 36-point performance on Feb. 5 against Philadelphia, which followed his 39-point marvel on Jan. 22 in Washington. Jared Sullinger, named the Eastern Conference’s Player of the Week yesterday, contributed his 13th double-double since Jan. 2 with a 13-point, 10-rebound night. Rookie Kelly Olynyk, who also appears to be building momentum, came off the bench with 14 points and 11 rebounds. In the manner of a pair of punch-drunk fighters holding on to each other, the Celtics and Bucks maintained a sloppy closeness in the third quarter. The Celts started with a 49-46 lead, gave it away to the Bucks four times, and righted themselves in the last two minutes with a 7-0 run that staked them to a 70-68 lead at the end of the quarter.