The Big Brothers Big Sisters of Massachusetts Bay received $2 million in donations from its Big Night fund-raiser Saturday night at the House of Blues. More than 1,000 people attended the annual soiree, which featured performances by Jason Derulo and Allen Stone, plus a special appearance by retired Red Sox slugger David Ortiz, who surprised the crowd with a coveted auction item — the chance to dine with him that evening. Big Papi’s offer went to the highest bidder, and raised $75,000 for the organization. Colin Mahony, a Big Brothers Big Sisters of Massachusetts Bay board member, spoke to the crowd about his experience mentoring his “Little,’’ who is now 26, and how it’s had a lasting impact on both of their lives. Another board member, Jeffrey A. Leerink, was honored at the event and given the eighth annual James J. Pallotta Award. Big Night was emceed by Big Brothers Big Sisters of Massachusetts Bay president and CEO Wendy Foster, who said she was “thrilled’’ with the outcome of this year’s fund-raiser and “overwhelmed by the continued support of attendees.’’