I'm big and tall....what do I do when others can't see by me when sitting behind me?

I'm pretty big and tall for my age (nearly 16, about 6ft 2in, and around185 pounds). A little while back I was watching a performance with my cl Downtown. When I took my seat, one of my clmates behind me kept on complaining she couldn't see the stage and my head was "too big" and some other things (I'm a calm person so it didn't really bother me). I really didn't know what she expected me to do. I offered her my seat but she refused because that would mean all her friend would have to move, as well as my friends.I couldn't switch seats with a friend because then I would just be blocking someone else (and I know they wouldn't be as rude about it). Now during the whole performance I did my best to slouch down and lean my head over (much to my discomfort). I really hate being criticized for something I can't control. I know she's a jerk, but at least she was honest (unlike most people who would just let my head obstruct their view, and maybe only politely ask me to move my head).