Nicked from a camping forum:
1. Camping is very tribal. The ultralight backpackers look down on the glampers for bringing most of the house, while the glampers smirk at the backpackers trying to get changed in a space the size of a coffin. Some campsites will capitalise on this, advertising themselves as ‘family friendly’ (screaming kids from 6am to 10pm), ‘dog friendly’ (same as kids but all night too) or ‘adults only’ (less kids, more alcohol).
2. No matter how carefully you plan, you will forget something vital such as tent poles, the pump for the inflatable mattress or spare underwear, or it will break on day one. Real campers will always carry a repair kit and improvise replacements utilising twigs, string and duct tape without conceding a trip to the shops.
3. Tent floorplan. Do not believe it. Tent sizes are a work of fiction. A two man tent will only take two small and very friendly men. A four man tent is the minimum for a couple while a six-man tent will only take two adults and a couple of kids. One-man tents are for masochists who don’t mind leaving all their gear outside and removing slugs from their boots in the morning.
4. Pop-up tents are amazing bits of kit that allow you to get a shelter up and usable in a couple of minutes. However, they will also take a combined degree in engineering and origami to get them back into the bag. All other tents will only fit back into the bag after being folded and rolled in a very specific way, which you will have forgotten since last year. The family in the next tent over will be packed and leave within 30 minutes.
5. Whatever the weather forecast, it will rain just as you are packing up, forcing you to put the tent back up in the house to dry it properly. Your house will smell of damp field for days.
6. All camp sites consist of 1 to 2 cm of topsoil on top of solid rock. You will not be able to put in tent pegs without using a mallet or handy shoe. When you do apply more force, most of the tent pegs will bend leaving you with less pegs and more large staples. Experienced campers will already have replaced the standard pegs with at least a few heavy duty ones that can be pounded into the hardest ground.
7. No matter how flat the pitch appears to be, during the night you will discover:
a) there is a slope which means you wake up with your face pressed to the tent wall; and/or
b) there is a large lump under the groundsheet precisely under your back
All but the hardiest experienced campers bring an inflatable mattresses.
8. The campers on one side will loudly discuss religion or politics until the small hours. On the other side will be a family with children who get up at dawn. This will remind you why you always pack earplugs.
9. Someone will bring a guitar. They will only know three chords and less than half the lyrics, but this will not stop them working their way through the collected work of Chris De Burgh, Roy Orbison and Chris Rea. Or Motorhead.
10. On cold nights it’s acceptable to wear your entire wardrobe – including a weeks’ worth of socks and a thermal hat – to bed.
11. It’s perfectly normal to queue outside a portable toilet at 7am wearing pyjamas, a raincoat, wellington boots and clutching a toilet roll. You may greet other campers with a nod or grunt but must avoid eye contact and attempts at conversation.
12. Standards of hygiene drop the longer you are camping. After a few days, a 30 second wash in freezing cold water with a facecloth counts as a bath. Clothing is selected based on the driest rather than cleanest options, and a quick rinse counts as ‘doing the washing up’. The kids start to resemble feral animals and love every minute of it.
13. Everything takes far longer than normal. Boiling water for tea takes ten minutes. Making dinner can take two hours and even getting water is a task. Experienced campers understand that this is one of the major joys of camping, and enjoy the slower pace of life for a few days.
14. Everything tastes far better when cooked outside. Whether it’s a single gas ring, a fire pit or a bottle of ale your taste buds will thank you for camping.
15. The fire loves you and wants to be close to you. That’s why no matter where you sit the smoke will always go directly in to your face. Singed eyebrows and smoky clothes are a small price to pay for the simple pleasure of poking a fire with a stick.
16. If there are insufficient chairs or suitable rocks for sitting on, the three-second rule means that any chair left unoccupied for more than three seconds is fair game. Folding the chair and taking it with you is generally considered poor sportsmanship.
17. Getting into a sleeping bag will instantly trigger the urge to pee, which is even worse when it’s raining. While new campers will struggle to get dressed and out to the toilets in the dark, experienced campers develop a bladder of steel – or keep a carefully labelled bottle handy.
18. At 3 am someone will trip over one of your guylines with a noise like a double bass being dropped. Your modified luminous guylines, solar lights and careful pitch selection minimise the chances of this happening more than once, but there’s always someone who forgets a torch.
19. Camping, especially wild camping, is the best place for stargazing and animal spotting. Your eyes will adapt to the low light and you will see more stars than you can count, spot meteorites and watch planets rise. In the morning you will often see rabbit or deer feeding, spy a cautious fox scout for food or just listen to the birdsong.
20. Lastly, experienced campers will know that one of the joys of camping is getting back home. The hot showers! Running water inside! Bone-dry duvets! En-suite toilets!
And yet, even so, they will be immediately planning their next trip away.
Especially where we live. That's why we'd need big sticks and cages... 
