If you look it up, in fact there are two such flags. One is called a pride flag (black and white horizontal stripes). From the description on the web site I looked at, it did not sound like it denoted "pride" but rather a rejection of the LGBTQ+ community. That sounds like small-mindedness (bordering on hatred) to me, not pride. There is another flag that represents solidarity with the LGBTQ+ community (the black and white horizontal stripes with an added rainbow triangle) and I like this message better. I think there could be a place for a different kind of flag for the het community: a flag that just acknowledges you are in that mainstream community. I think it could promote tolerance, as by showing that flag, you are implicitly acknowledging that there are other types of equally valid sexuality. I should say I am a mathematician, not a social scientist, and heterosexual, so I may be missing important elements of this issue.
I started thinking of this because of my paper mache box making hobby, which you can read more about in other posts. My daughter had told me that making boxes with the various sexuality flag designs could be quite sellable. I had made a box for a heterosexual friend and thought that with my theme I should have a corresponding design. This is what I came up with, and I think it would be appropriate for the het flag to be blue and pink with the connotations I was suggesting above. I will leave it up to a graphic designer to make a nice looking design with these two colours in equal proportion.
