A Roman Catholic priest from Walpole has pleaded not guilty to groping a 21-year-old man at a Canton Park and Ride lot. The Rev. Emile Boutin, a youth pastor at Blessed Sacrament, pleaded not guilty to indecent assault and battery on Monday in Stoughton District Court. Prosecutors say the alleged victim pulled into the lot about 8:30 a.m. on Monday and walked into the woods to go to the bathroom. The man, whose name was not released, alleged that another man followed him, and touched him through his shorts. The alleged victim got his assailant's license plate number and called police.