[creep]

I'm not a man, but mentioned in another comment that manspreading is more about comfort due to having testicles and I can sympathize with that. If the dude is significantly impairing my ability to sit straight on the seat, I will usually spread my legs a little wider to force him to move a little, but if not-- if he's just taking a bit of room-- it doesn't matter so much.

I don't think it's a problem that needs to be solved. Imagine if your discomfort was visual: you're walking on crutches or you have a cast. People would naturally give you more room because they don't want to cause you any pain. Men are not about to say, "excuse me, ma'am, my balls are sweaty and it's not appropriate to adjust them to a certain degree in public, and besides that I don't want to crush them between my legs, so if you don't mind, please forgive me if I take up a bit of room on the seat."

[eridius]

Speaking as someone who used to be a man... that explanation is complete bullshit. Whoever told you that was lying. Men can clamp their legs tightly together without even any testicular discomfort[1]. The only legitimate reason for manspreading to be more prevalent with men is that men tend to have larger thighs, but even that doesn't excuse the practice. Keeping your legs spread a bit may be more comfortable, but that's true for everybody, it's just that women are taught to keep their legs together when sitting and men are not.

In reality, men manspread because they can. Spreading out your body to take up more room discourages someone from sitting next to you. This includes spreading out your shoulders and keeping your arms away from your body too. Most men, if confronted, will defend the practice by saying that they'll move if someone wants to sit next to them. But, though they may not want to admit it, they know that they're intentionally discouraging anyone from sitting next to them, and that most people on mass transit will choose to stand rather than ask a complete stranger to stop hogging the seat.

[1] Under normal circumstances. I'm sure there are medical reasons why someone might have overly tender testicles and experience discomfort doing this, but for the purposes of this conversation we're talking about people without any medical issues.

[creep]

I also make attempts to discourage people from sitting next to me. This behavior cannot be policed. If you want to sit next to a guy spreading his legs, simply ask him to move over. It's courteous not to attempt to discourage people from using public transit as intended, but it's not a gendered issue that needs widespread media attention chastising males.