I never heard her say “ovular” but “herstory” was something she’d said unironically. I’m sure you’ll be shocked to know that she was a Women’s Studies major.
Martin Amis wrote a short story based on that idea of gay/straight stigma reversal in his compilation of short stories Heavy Water.
I’m pretty sure I’ve heard it being used as a mild term of ridicule (and I’m pretty sure I’ve heard it used by straight and gay people alike) - I think it would have been when someone did something self-consciously heterosexual, to be told “well, that’s very straight of you”.
A gay guy I knew had never really thought about marriage (or even a longterm boyfriend) until the gay marriage bans starting cropping up. Now, not only is he helping out gay marriage causes, but he wants to get married some day.
Which prompted “I never thought I’d end up so… so… straight…” said with some mild disgust, but mostly affection.