Fetching the paper in your dressing gown and slippers is an indelible mark of eccentricity, especially if this involves a 10-minute walk through a busy shopping area. To an eccentric, wearing a dressing gown means you're dressed. It's not as if you're going to the shops in your pyjamas. Although it should be mentioned that eccentrics often travel far and wide in their pyjamas, albeit with their outdoor clothes over them.
Eccentrics have a highly unusual policy of eating things that they like. Honey and cheese sandwiches are a favourite. In a restaurant, an eccentric will often have a three-course meal, each one of them a dessert. After all, if desserts are your favourite, why waste time with anything else?
Eccentrics are fantastically healthy. This is not just down to their diet of peanuts and hake. It's because they're stress-free. Nothing in the modern world is of any concern to them, apart from the technical difficulties involved in building their bonsai perpetual self-watering system.
Eccentrics always have one trade mark item of clothing. Often this is a hat, on the basis that once they've put one on they forget it's there for the next 13 years. Sometimes, eccentrics wear things that weren't designed as clothing but which prove very practical, such as a two-man tent.
Odd beliefs are the trademark of the eccentric. A common one is that stepping on carpet brings bad luck. Or that aliens are living among us in the form of cats. Never ask an eccentric to explain their beliefs as this will involve their world view. This is bound to be odd: that the world is flat, or it's going to end, or is, in fact, the eye of a blind Cyclops crashing through space with only the sun's warmth to guide him. Whatever the view, it's unlikely to help you with the carpets or cats.
Eccentrics often get involved in politics, generally on a single-issue ticket such as banning reversing in car parks. They will always get at least 100 votes, presumably from disillusioned Monster Raving Loony Party voters. Occasionally, you'll see people talking to themselves in the street. These aren't eccentrics, these are idiotic people with idiotic mobile phones. Real eccentrics sing to themselves in the street - and not under their breath, either. The key to all eccentric behaviour is that they don't care about what other people think about them. And you can't get more eccentric than that.