Zero-sum gender.

Rowdy mentioned to a coworker that I have more power tools than he does. "Wow," the coworker said, "doesn't that kinda challenge your masculinity?"

In one sentence, so many layers!
1) Power tools are masculine. Owning power tools indicates, or perhaps causes, masculinity.
2) One would not expect a woman to do anything masculine.
3) If a woman is masculine, this makes her partner less masculine.
4) If a man isn't masculine, that's terrible.

All of which is particularly unfortunate considering that power tools are so useful. I didn't buy an electric drill to feel like I had a big swingin' cock (when I wanted that, I bought a big swingin' cock); I bought it because I was assembling furniture for my old apartment. Is it feminine to sleep on the floor?

But the interesting part for me is step 3. It's the idea that there's a limited amount of each gender role in a relationship, so if one partner is more masculine, the other must be more feminine. You see this a lot in the way certain people approach homosexuality--the idea that every lesbian relationship is butch/femme, or every gay relationship top/bottom. "Which one of you is the 'man'?" I think it even underlies more outright homophobia--how can you have a marriage or raise a child if you don't have people playing two distinct roles?

It's a bizarre extension of this thinking to be in a heterosexual relationship, but violate the unwritten rules just a tiny bit, and get "which one of you is the 'man'?"