Alcohol consumption is a relatively common way of relieving stress, even if it is for the short term and with side effects.
When consumed in small quantities, alcohol may stimulate the brain and give a mental small boost, however that's generally not the effect people are aiming for when trying to relieve stress. In moderate quantities alcohol relaxes the body and dulls certain areas of the brain.
One of the problems with alcohol consumption is that some people drink not with moderation, but with the intent to get wasted - such 'drinking to forget' behavior might suppress stress effectively for brief moments, but the resulting state brings many unwelcome side effects and leaves much to be desired.
Alcohol is often thought of as a social lubricant; drinking in a social setting may help relieve stress through social interaction rather than physical effects. It may become a habit to change or adjust behavior in such a relaxed social setting, and taking a sip of an alcoholic beverage may act more like a conditioned catalyst for such a behavioral change.
In conclusion, drinking is not one of the better and safer ways to relieve stress.