For first-time visitors to Bulgaria*
There is always a great many people playing chess in the park opposite Bulgaria's National Theatre in Sofia. They wouldn't mind at all if you were to produce a piece of advice on their game, or even if you move one of their pieces on the board for them.
Then invited to a buffet party in Bulgaria, it is recommended that you demonstrate good manners, modesty and self-restraint by waiting for at least 45 minutes before tucking into the food and drinks.
Learn It by Heart
For foreigners in Bulgaria, there is a stock answer to the question: "What do you think of our country?" It goes like this: "Az haresfa shopski salat i hubavi bugarski momiche" (I like the shopska salad and the beautiful Bulgarian girls). Any deviations from this correct answer could lead to severe embarrassment – or even criminal prosecution.
Then driving along Bulgarian motorways, you will soon notice that the oncoming cars periodically flash their headlights at you. This means that you are driving too slowly on a no-speed-limit section, so make sure to slam down on the gas pedal without delay.
A typical Bulgarian wedding is a quiet and peaceful affair. If invited to one, don't forget that it is traditional to grope the bride on the sly, thereby expressing your implicit approval of the bridegroom's wise choice of life partner.
You will notice a couple of small bowls on the tables in many Bulgarian restaurants: one full of red flaky stuff and one of vinegar with some bits of white stuff floating in it. These are the traditional Bulgarian condiments for improving the flavour of the otherwise awful Bulgarian lager. Simply dump a couple of teaspoonfuls of the white stuff into your beer glass, and embellish the foam on top with a generous sprinkling of the red flakes. Your Bulgarian friends would appreciate it highly if you would spice up their beers for them while they're off washing their hands.
At Your Service
Sofia cabbies provide shoe-shines at no extra charge. A local law requires that they each keep a box of brushes and various colours of shoe polish in their cabs, to be used if the customer should so desire.
In Bulgaria it is considered good luck to touch a policeman's hat, and the country's law enforcement officers have absolutely no problem obliging.
*Pleeease, exercise a modicum of common sense!