nut up v. to become bold, courageous, or forthright; to sack up, man up. (source: Double-Tongued Dictionary)
Further reading
Ever wonder what medieval England looked and sounded like? In Old English, the word hord meant “treasure” and your wordhord was the treasure of words locked up inside you. A delightful new book uses the language of that period to create...
Sure, there’s winter, spring, summer, and fall. But the seasons in between have even more poetic names. In Alaska, greenup describes a sudden, dramatic burst of green after a long, dark winter. And there are many, many terms for a cold snap...