Picnic boy believes that a train is a place where you can sit down and trough through some grub in quiet and comfortable surroundings. This person is completely oblivious to anyone else, so much so that you can't help but admiring him, until he starts eating that is. The sight of someone sitting barely two feet opposite you, chomping their way through a bag of Nobby's Nuts is never pleasant. It's hardly acceptable or nice to look at when you've just married the masticator in question and you're in that short period where you still love them, let alone Picnic Boy.

But it won't stop at the rustling of peanut packets. In the rucksack will be something you could never imagine eating on a train, like a family size Bowyer pork pie accompanied by a small bottle of HP sauce. He will noisily wrestle with the wrapper, extract his trusty pen knife and cut a quarter of the pie with it. If you get a chance, grab it off him and stab him. If you don't manage this, you will be forced to watch him pour the sauce over the pie and start to eat it. Pastry crumbs and gobbits of pork pie jelly will be sprayed asunder. He hasn't got the hang of serviettes or the concept of cleaning up after himself and so even though the pie will have noisily been devoured, you'll be left sitting for some considerable time amongst a river of spilt brown sauce, unsuccessfully trying to avoid looking at the large bit of pork fat deposited just above his top lip.

There are various types of other people who think it's ok to eat on a train full of weary commuters. Sitting next to someone and then proceeding to gobble a Big Mac and fries seems hugely impolite to me. The same with a big garlicky sandwich or a packet of cheese and onion crisps.  It assaults all the senses.

The worst are families on a day out especially those that leave early in the morning. Why travel then? It's more expensive and completely jammed. But no, they want to be at the front of the queue for Madame Tussauds, so they can stand next to a crap wax figure of David Beckham and have their picture taken. Do they think they'll convince their friends that they were actually standing next to the real Golden Balls? Who knows. Whilst dreaming of this attempt at social oneupmanship, out will come the sandwiches for breakfast, along with the thermos flask and cartons of Ribena, and don't get me started on Müller fruit corners. The parents should be reported to social services.
Like Picnic Boy it's not just the visual impact of watching people eat, it's the noise of chewing and packets rustling and above all the smell, which not only lingers in the carriage and turns rancid, but lingers too on their breath.

How to spot Picnic Boy
He will not be wearing a suit as he doesn't own one. Instead he'll favour the type of jeans worn by Jim Royle from the Royle Family. He'll wear trainers that no one would ever steal, with boring grey socks to match. He's a great fan of The Inbetweeners. He's very likely to work in IT and not get out much because he spends all his social time playing computer games, pitting his wits on the internet with another nerdy bloke from Japan or Bulgaria. He'll be wearing a black faded t-shirt with some smart arse slogan, which is generally ironic given his appearance and general demeanour such as:

• Cover me in chocolate and throw me to the lesbians
• You can look but don't touch
• Rehab is for quitters
• No I don't want bloody cashback
• Jesus is coming. Look busy
• I'm not a gynaecologist but I'll take a look

He'll also have a stubbly type half beard, mainly because he's too lazy to shave more than once a week, but also because he isn't actually that hirsute so it doesn't grow that much.

His food will be stashed in a smallish rucksack and he'll always have his headphones on, because he's not used to having social intercourse. Or sexual intercourse for that matter. All his hobbies are solitary and don't involve old fashioned conversations with other people. On the upside this means that wanking can remain a favourite hobby.

Survival tips
I don't have any tips for surviving Picnic Boy and his chewing chums, but perhaps other commuters who like me are appalled at someone masticating on the 7.48, should lobby to get a specially designated food carriage appointed on each train. We could do a Twitter campaign. It worked in getting the News of the World shut down, so why not? It could be a bit like the old smoking carriages they had in the days before politicians thought governing meant nannying. They could all sit in there with the doors locked, so the detritus of part consumed food and the swirling smell of stale chip fat and Worcestershire sauce flavoured Nik Naks can be contained. Excellent.

Can't think of a hashtag though.