The following things we do at the gym are – to the observer (e.g. any female) – objectively very weird.
Dropping weights
Nowhere else in life is it acceptable to throw something you're done using on the ground. Imagine if, after dinner, you smashed your plate on the floor? Or if on the plane, you just littered your boarding pass in the aisle?
At the gym some men drop weights. Rather than politely lowering them, some just throw them down with abandon, normally irritating everyone around them. It also damages the equipment that someone else must eventually pay for.
Mansplaining
At my mostly-male gym, guys mansplain to other guys a lot. Especially when it comes to form and technique. I don't see this necessarily as a bad thing – especially if you see someone who's about to hurt themselves. Some men treat this kind of advice as an "emergency only" interjection though.
However, other men mansplain to others like a dog would - urinating over a spot another dog had just pee'd on. It's an odd territory-marking trait.
Some men also mansplain to women at the gym. I wonder if they think it's a way to meet girls. It's not. Women don't want our advice in that space, period.
We're either super-polite to each other…
Or super rude to each other. I will make an age-based generalisation here: if you're under 50, you're probably overly polite to other men at the gym. We have a kind of sign-language to ask each other, "are you using this machine?" Even to a guy on the other side of the gym, exercising a different muscle group. It's always met with an over-apologetic response, such as a sheepish, "oh, no, no, it's all yours!" complete with overt hand gestures in case they didn't get the message.
However, men over 50 can be wildly rude to each other (especially towards younger men). Perhaps it is the perceived threat of virility, but you'll notice that older dudes use others' machines without asking, they huff and puff and look aggrieved at younger guys, and they take up a lot of physical space (such as laying multiple dumbbells all over the floor).
Like with mansplaining, it feels like some older gym-going men are trying to enter another pissing contest.
Unhygienically at home
Going to the gym in the immediate aftermath of lockdowns was great, as everyone was very vigilant about cleaning their equipment. They were also overly disciplined in their interactions. Now, we've largely stopped wiping our sweat off benches. We're leaving visible and sticky butt-prints on the machines. We back to behaving the same way we would in our own filth and squalor at home.
Some men also grunt their way through heavy sets, a behaviour that would never be acceptable in any other social setting. Some don't use deodorant, offending everyone within a 10m radius. Some fart and just walk away. Some talk or text on their cell phones whilst occupying a machine others want to use. And some stare – like, really stare – far longer than socially appropriate, making you want to leave.
Vanity
We all go to the gym to appease some form of personal vanity, but most of us keep that quiet. However, there are outliers. The men who flex in the mirrors. The men who boast about how much they can lift. The men who do all their personal grooming in the locker rooms (a word to all, shave at home! You're still in public!)
I am guilty of the occasional gym selfie – and lots of women are too – but this also counts as one of the weird and vain things men do. I'm not going to stop doing it because sharing your gym progress is great motivation to keep coming, but let's all acknowledge that taking mundane photos of yourself is something others observe us doing. And they judge us for it.