The celebration of one's heterosexuality. It is not a bigoted or intolerant thing to proclaim-it is simply stating the truth, that you are straight and not ashamed of that fact. Modern society has come to look down upon the mainstream as being unwilling to accept those who are different; in doing so, it has itself become unwilling to accept those who make up the majority. There is nothing wrong with being homosexual, there is nothing wrong with being bisexual, and there is nothing wrong with being heterosexual.
Has the gay/lesbian/bi/transgender population been oppressed throughout history? Yes. Does that give said segment of society the right to point fingers and call names? No. They are displaying the very same actions they claim to be against. Their activism in supporting their own rights has gained them much in recent decades, but the lengths they have gone to to demean the heterosexual community as being closeminded has taken away some of the credibility they had as a social movement.
There is nothing wrong with being heterosexual, and to deny us the right to be proud of our way of life is to press upon us the same injustice that was for so many years laid upon the homosexual/bisexual/transgender community. If equality is really what you are aiming for, why not acknowledge that heterosexuals can be happy with the lifestyle choices they have made? Straight pride is no more bigoted and exclusive than gay pride, and it was never meant to be.