After much observation in both men of women alike, it has occurred to me that people in general, like to be seen as deep. One of the quickest ways of appearing deep is to say, "or is it?" after somebody else has said something. Or is it? You can get a similar effect simply by transposing the key elements in any sentence. For example, when someone says, "Women are the power in the home", you could immediately reply with, "Yes, but home is the power in the woman". Just make sure there isn't anyone even deeper in range who might just chip in with, "I think you'll find that power is the home of women" ~_~
Humans, like fish, get more unpleasant looking the deeper they get. If you're going to be deep, don't wear bright colours. Deep people, I've noticed, always wear black to signify their great undiscovered depths. Sequins, on the other hand, have the opposite effect!
Including foreign phrases in your conversation is a 'sine qua non' of being deep, preferably phrases nobody's ever heard of :p You won't get away with 'Frère Jacques, dormez-vous?' in all but the most shallowest of company.
Bitter hollow laughs are great for added depth. After someone says something completely innocuous, such as "they're bound to have Hoover bags in the corner shop", a bitter hollow laugh will show that you know through long and bitter experience that life isn't that simple - you're deep!! Even if you're proved wrong, you can retrieve the situation by saying, "Yes, but is there a shop in the bag?" or "Plus ça change, plus ça Hoover bag". Neither of which makes any sense at all, but if you're wearing black, people will assume you've found meaning at a much deeper level than they can penetrate.
Another excellent way of showing how complex and brainy you are, is by answering any question with the phrase, "It depends on what you mean by that". Don't use this too much though, otherwise someone might turn around and say, "What do you mean by meaning?" Which then would've meant that you have subjected yourself to a battle with the other person whereby you try to 'out-deep' each other. You'll then be at such depth that your head might implode with the pressure.
A vital accessory for deep people is a difficult book, preferably by a Russian author specialising in poverty, misery and death. It's best to buy this book second hand if you can, so even if you don't get past page 2, it will still look as though you're reading it for the 5th time for hidden depths.
It's equally vital to steer clear of any ball games if you want to appear deep... Juggling, bouncing, heading and dribbling are completely contrary to cool pensiveness. The other enemy of depth, and those that live at that level is the word 'bollocks'. You can't change the word round, it doesn't translate, and even, "or is it?" invites the final authoritative answer, "Yes, it is."