red flag

忘年会、新年会が入ってくるシーズンになりました。飲みすぎには注意したいところです。
6 Signs You Drink Too Much

Most people who binge drink don't fit the definition of an alcoholic, but there aren't just two camps of drinkers, say experts: Many of us are somewhere in between. To find out where you fall on the problem-drinking spectrum, read on for these surprising signs you may be drinking too much.

You're a Weekend Warrior

If you don't drink daily but are drinking regularly, such as every Friday night, that's a red flag," says Dr. Smith. While research shows that having about seven alcoholic beverages per week lowers your risk of diabetes and cardiovascular disease, abstaining all week only to guzzle five or six glasses in a single sitting negates any of alcohol's potential health benefits. Moreover, binge drinking can raise blood pressure and interfere with certain medications. "Plus, it's easier for women to suffer acute alcohol poisoning that could lead to death because it could take only six or seven drinks for someone who is 5'3" and 115 pounds, while it may take twice that amount or more for a larger man," says Dr. Smith.

ここでのred flagは日本語でも言いますが、「危険信号の赤旗」（『ジーニアス英和辞典　第４版』大修館）という意味で使われています。英語でも同じように赤い旗、red flagという形で使えるのですね。LDOCEには、"[AmE] something that shows or warns you that something might be wrong, illegal etc"と定義されています。また、red flagは過去にもブログで先輩が取り上げられています。http://d.hatena.ne.jp/A30/20101208/1291792396
簡単な単語ですが、日本語の「白旗」も英語で日本語と同じように"white flag"で表す事ができますね。日本語でも英語でも同じような表現ができる言葉が存在することに、言語の面白さを感じます。（Astroriver）