YOU get used to others' eating habits.
From the people you sit near at work - the grazers, the 3pm chocolate fixers.
Then there's your family - the big breakfasters, the no-breakfasters and the secret midnight eaters.
You probably notice what's on the rest of the world's menus too -I acknowledge the greedy seagulls, the peckish pigeons and my cat, the hungriest creature in the whole land.
Despite noticing all of this munching activity all day every day, not once have I snapped a photo of anyone or anything eating.
However, with the internet throwing up a different craze almost every minute, I suppose it wasn't long until a new trend emerged.
And here it is: a Facebook group called Women Who Eat On Tubes (WWEOT), which was launched in London, and has attracted more than 20,000 people.
The founders call it "observational not judgmental".
I call it embarrassing, for the people behind it - not the strangers photographed. And creepy.
What happens is people take secret pictures of women eating on different train lines then post the photos to the page with a caption saying the time, the route they are on and what they are eating.
So whether you are nibbling on sweets, enjoying a sandwich or grabbing a banana on the go, if you are a woman you are now at risk of being 'caught' on camera.
Bizarre isn't it? There have been plenty of train trips when I've clocked men gobbling down a kebab or two, yet no-one has tried to 'stranger shame' them.
Why is eating in public places so frowned upon for women? You could argue that it is bad etiquette to eat on public transport.
BUT times have changed and eating on the go is usually just about not having enough time to sit at a table and eat a proper meal.
Almost everyone does it. One of my colleagues says she gets disapproving looks for eating cereal from a Tupperware box on the way to work.
Well, at least she's trying to have a proper breakfast, even when she's on the number 38 bus.
One of the worst things about WWEOT are the comments under the pictures. Things like: "Marshmallows at 6.35pm. Interesting choice," and "Don't even think about asking for a bite".
Who has the right to judge where and when you enjoy your marshmallows? It's just bullying.
I like the internet for the random things it throws up - the Sellick Waterfall Sandwich, the baby in the car wash and the sneezing wee panda.
But this stranger shaming is being taken too far. Can we please just live and let dine, people?