So you just had a quick happy hour with your colleagues and are ready to hit the road. You think you are safe to drive after having had just two drinks. But if you're pulled over, you may be blowing a lot more alcohol into the Breathalyzer than you think. Why? New research shows that we may be drinking more alcohol than calculated when we drink in a bar.

A study by the Alcohol Research Group at the Public Health Institute looked at around 500 different bar drinks at 80 bars and restaurants in Northern California. They found that drinks served in a bar are up to 50 percent larger than the standard size and that the alcohol content varied from what was expected in the drinks.

How is this significant? A glass of wine served in a bar may actually be the equivalent of 1.5 standard servings of alcohol and may vary in alcohol content (that is, 14 percent alcohol instead of 12 percent). A serving of beer is 12 ounces, but a typical "glass" of beer in a bar may contain up to 16 ounces. Mixed drinks also had more alcohol content than the recipes specified — almost 50 percent more in certain cases. So if you had two glasses of wine, you may have really consumed about three servings.

Given that, here is a summer alcohol quiz from your friendly doctors. Take it and see if you are ready to drive safely.

1. A standard drink is equal to:

a. 16 ounces of beer, 12 ounces of malt liquor and 8 ounces of wine.

b. 12 ounces of beer, 8 ounces of malt liquor and 5 ounces of wine.

c. Anything on the happy hour special.

2. Women vs. men:

a. Women will get equally as drunk as men, drink for drink.

b. Women will become more drunk on the same amount of alcohol as compared to men.

c. Women make better choices when they are drunk.

3. Health benefits:

a. A couple of glasses of wine taken daily are recommended for everybody for their heart health.

b. Moderate alcohol intake may reduce risk of heart disease, but alcohol has also been linked to sudden death in people with heart disease, and excessive alcohol leads to damage of the heart muscles.

c. Alcohol makes you irresistible to the opposite sex.

4. You are probably drunk and should not drive by the time you are showing signs of:

a. Clumsiness, impaired speech, excessive emotions, inability to walk.

b. Feelings of relaxation, reduced social inhibitions, euphoria.

c. Having a conversation with a potted plant.

If you answered "b" to all the questions, congratulations — you got them right. For clarification on the last question, remember that more than one drink in an hour makes you unsafe to drive — and it may take the body up to two hours to clear one standard drink.

The magic number for safe driving on the road is zero drinks. And you can be above the legal limit of 0.08 alcohol content when you are just starting to "catch a buzz."

Drs. Kay Judge and Maxine Barish-Wreden are medical directors of Sutter Downtown Integrative Medicine program in Sacramento, Calif.