The word "mordida" (mor-DEE-dah) literally means bite, but in Mexican slang, it is used to mean a bribe, usually one paid to a public official. The more formal word for a bribe is soborno. An example could be, "I got caught speeding in Mexico and I gave the cop a mordida so he wouldn't give me a ticket."
Corruption and Mordidas in Mexico
The Mexican government has been working to combat corruption, with limited success.
The custom of paying mordidas in government offices is not as widespread as it was in the past. It's best to avoid paying mordidas whenever possible so that you're not playing into and reinforcing this corrupt system. It is possible to travel, live and do business in Mexico without paying mordidas.
You are most likely to come across the dilemma of mordidas when you're driving in Mexico and stopped by traffic police. These poorly paid police officers will generally disregard traffic violations in return for a cash payment. In some situations, a refusal to pay a mordida will result in the cop letting you off the hook because he can't be bothered to write up the violation. In other cases, they may confiscate your drivers' license or the license plate of your vehicle so that you are forced to go to the police station to pay a fine. Remember that fines for traffic violations in Mexico are not terribly expensive, but it is a hassle to do the required paperwork if you do have to go into the police station.
If you pay a ticket within five days of receiving it there is usually a discount, so it is advisable to pay as soon as possible.
Also read: Tipping in Mexico
How to Pay a Mordida
If you are in a situation in which you feel you must pay a mordida, but you don't know how to broach the topic, the subtle way to mention it is to ask: how can we resolve this?
"Como podemos resolver esto?" Which will probably result in a price being mentioned. It is quite common to haggle about the amount of a mordida, so don't feel like you have to pay the initial amount requested. If you are obviously not Mexican, you will probably be expected to pay more, so do bargain to bring the amount down.