If there is one thing that can make me a bit emotional, it is discrimination against a minority group. It doesn't even particularly matter which minority group, to be honest.
It's something that's been part of the way I think and act for a very long time. I've always incorporated egalitarian ideals into my world view. To be fair minded and just is an intrinsic part of a positive view of myself. If I cannot see myself as being overwhelmingly in line with rational, egalitarian thinking, I become quite moody and depressed.This is made all the worse in moral and ethical issues.
So when other people make comments that have a less-than-subtle discriminatory vein, I am compelled to comment, both by desire and by my own moral standards, even if in a non-confrontational manner.
When I cannot comment, when I cannot protect or defend a target of discrimination, I feel powerless. Weak. Complicit in the actions of the perpetrator.
While aware that I only have anything approaching complete control in regards to my own actions, and the amount of control I have over others behaviour is inherently limited, I am also aware that if no one does anything, other bystanders are also less likely to intervene, and the cycle continues.
Someone must be the first.