man up

Japan Times Online, May 21の見出しです。
Avoid excuses, man up, Obama tells black graduates
オバマ大統領の、文章ではなく、演説を伝える記事なので、見出しに使われている "man up " は口語的な表現のようです。　記事の一部を抜粋します。
Delivering a commencement address at the all-male private liberal arts college in Atlanta, Obama spoke in deeply personal terms about the “special obligation” he feels as a black man to help those left behind.
...
If they get a law degree, he told the graduates, they shouldn’t defend only the powerful, but also the powerless. If they get an MBA and start a business, Obama said, they shouldn’t merely try to make money, but also consider the broader purpose their business might serve.
社会の強者になることだけを目指すのではなく、弱者を助けれる人間になれと説いているようです。　"man up" の意味を辞書で確認します。
・Wiktionary: (idiomatic) to "be a man about it"; to do the things a good man is traditionally expected to do, such as: taking responsibility for the consequences of one's actions; displaying bravery or toughness in the face of adversity; providing for one's family, etc.: I was wondering when he would man up and marry that girl he knocked up.: You need to man up and confront your boss about his behavior.: Hey son, man up, ok? There will be time for tears later.
・Collins Dictionary: intr, adverb (US, informal) to adopt a stereotypically masculine approach or course of action:
オバマ大統領が "man up" と言ったのではなく、Japan Timesの記者が "man up" の表現を選んだのですが、 "man up" にはやはり、引用した後者の辞書の意味がまとわりつきますね。