I've been waiting staff for over two years now, and there's definitely some correlation between men and meat, and women with poultry and fish. We've started offering a choice of red cabbage, salad or vegetables recently, and it's normally then men who have red cabbage or veg, and the women who have salad, unless it's something where one of the options just wouldn't go well, like a pie and salad.
I do expect the men to have the heartier, meatier things, so I might look towards them when asking who's having a meat dish, or I might just look at whoever replied to me when I greeted them, depends on whether I've spoken to them before. I wouldn't dream of putting the food down before they'd told me who was having what though, because it makes me look a fool when I get it wrong, and you never really know. Unless it's our Monday regulars, because I know that David will have the pie or steak with chips and veg, and Linda will have the other, often fish or crab, with salad and new potatoes (except this week they swapped the salad and the veg over and it confused the life out of me, I thought the order had been written wrong! We got a good laugh out of that when I checked we'd got it right with them).
Other random observations I've made are that men are generally English mustard and ketchup people, while women are Mayonnaise, and if they have mustard, Dijon. I'm surprised at how many men order cappuccinos though, I thought that was a "woman's drink". Women rarely have real ale in my experience, but I don't blame them, none of the locals will go near the stuff for fear of severe repercussions in their stomachs for the next few days. We did rib one of the locals a lot when he occasionally had a martini, but it was just part of his oddballness, and he was normally too drunk to probably even remember he'd had one by the time he ordered it, between asking for glasses of water and flicking it at everyone and trying to get non-swimmers to go skinny dipping.
As for me, my girlfriend's always laughing at me because I LIKE MEAT. RAWR! I get meat withdrawals if I haven't had any in a while. Although I don't like sausages or burgers with herbs and all that rubbish in, if I wanted something to taste like a leaf I'd go into the garden and chew on the grass.