Drinking is bad in massive amounts or on a regular amoung. There's nothing wrong with having a glass of wine at a wedding or something like that. (Ian Mackaye, who wrong the Minor Threat song "Straight Edge" has even said "It never meant you couldn't have a drink every once and a while") However, most straight edge people chose to avoid it completely since it's a mind-altering substance. However, so long as you're over 21 (or of age in your country) and don't have an addictive personality, having a glass of wine at a wedding or one beer at a bar (very rarely) shouldn't completely kill your "straight edgeness." It really depends what the term means to each person, some even include being a veagan as a part of the lifestyle. However, most don't.