In the first Fire Emblem OVA, during the bandit attack in Talys, the archer Gordin saves a soldier by shooting the bandit attacking him in the rear.Thankfully she's wearing a full-body bulletproof suit, but it still hurts her and she quickly takes payback against the responsible. An early episode of Dirty Pair has Yuri getting shot in the ass during a mission.In Destiny of the Shrine Maiden, when Chikane takes out the Necks of Orochi, Nekoko ends up getting an arrow in her ass.In one City Hunter story, Ryo gets shot in the rear with several arrows by the person targeting the Idol Singer he's been hired to protect.Happens to Amata in Aquarion Evol a few times to stop him from floating/his emotions getting out of control.Compare Butt Biter and Literal Ass-Kicking.
If you happen to deliver one of these, a " turn the other cheek" one-liner is always good form. In several wars, being shot in the ass was known as a "million-dollar wound", because it was serious enough to get you medically discharged and shipped home but not permanently debilitating in any way once it had healed, and, as such, worth a million dollars to a war-weary grunt. Of course it's still pretty undignified, especially as far as deaths go.
In fact, survival experts often (semi-seriously) advise people confronted by guns to stick out their butts to offer them as the least risky targets. But of all the places on the body where one can get shot, the butt has the greatest chance of not being life-threatening and causing any permanent damage when treated properly. In Real Life, any gunshot can kill, especially if left alone long enough to get horribly infected. Usually Played for Laughs because, seriously, a bullet to the ass? The ultimate in Amusing Injuries which, as well as being Only a Flesh Wound, is an assisted Literal Ass-Kicking by a bullet to the buttocks. Exactly What It Says on the Tin - a character takes a bullet to the hindquarters.