The last thing any bride wants is to be upstaged on her big day, especially by an A-list friend! Check out which famous starlets have served as bridesmaids — and even maids of honors — at their besties’ nuptials … Lady Gaga toned down her usual over-the-top wardrobe to be a bridesmaid in her best friend Bo O’Connor’s wedding in Cabo San Lucas, Mexico on June 8, 2013. The 27-year-old singer matched her fellow bridesmaids, donning a pink champagne halter-top dress with a plunging neckline.