what @Gingerninja said, and I have all my fingers tattooed and that was a very easy spot for me,many people say knees and elbows are really bad and my knees and elbows were also easy for me,
and @Donnelly1991 ,no offense but it sounds like your sister really doesn't have too much to compare pain levels to with only 2 small tattoos,
don't let the pain discourage you,it's not as bad as you think,and if you are that worried,then maybe don't get tattooed.