Elle King is showing off the latest addition to her tattoo collection. The “Ex’s & Oh’s” singer, 34, took to Instagram on Thursday, April 4, to reveal the new body art plastered on her rear-end, which is dedicated to the men who have helped her with her son, Lucky Levi, 2, whom she shares with ex-fiancé Dan Tooker. “I always said I’d get my baby daddy’s name tattooed on my butt…so I did,” King wrote alongside the slew of photos of herself laying on her stomach while the artist did his work. “I got ‘brethren’ for the men helping me raise my son,” she continued of the meaningful word. “I love yo…