"Standing up" means being on your feet or rising from sitting or lying.
It can mean defending yourself or others when used with "to" or "for".
Used with an object, it can mean failing to show up for a meeting or date.
People who work sitting down get paid more than people who work standing up. Ogden Nash
Writing and travel broaden your ass if not your mind and I like to write standing up. Ernest Hemingway
Acting is standing up naked and turning around very slowly. Rosalind Russell
I have remarked very clearly that I am often of one opinion when I am lying down and of another when I am standing up... Georg Christoph Lichtenberg
But the problem is that when I go around and speak on campuses, I still don't get young men standing up and saying, 'How can I combine career and family?' Gertrude Stein
He who really wants to die will not complain if he is buried standing up. Mexican Proverb