Miley Cyrus, 21

Miley Cyrus turned 21 today. Born Destiny Hope in Tennessee, Cyrus, daughter of Billy Ray Cyrus, got her start as Disney's Hannah Montana. She earned her first hit as Miley Cyrus with "Party in the U.S.A.," breaking the record for "Most Charted Teenager." Cyrus later took on some acting roles. After disappearing from the public eye for a while, Cyrus remerged with a whole new sexy look. She caused controversy with her risqué MTV VMA performance, and appeared nude in her "Wrecking Ball" music video. However, all this controversy paid off, giving her a number one single and a number one album.

Nicole "Snooki" Polizzi, 26

Nicole "Snooki" Polizzi turned 26 today. She appeared on MTV's The Jersey Shore, and with her wild antics, gained popularity, making Snooki a household name. In high school she was a cheerleader, and wanted to become a veterinary tech. Instead she became a reality superstar, currently on MTV's Snooki & JWoww, and appeared on ABC's Dancing with the Stars. She gave birth to her son, Lorenzo, in August 2012, and is engaged to Jionni Lavalle.