nut up v. to become bold, courageous, or forthright; to sack up, man up. (source: Double-Tongued Dictionary)
Further reading
Old. Elderly. Senior. Why are we so uncomfortable when we talk about reaching a certain point in life? An 82-year-old seeks a more positive term to describe how she feels about her age. And: a linguist helps solve a famous kidnapping case, using the...
Tracy in Beaufort, North Carolina, says her grandmother, aunts, and uncles used to try to calm down an upset or bossy person with Well, don’t get astorperious! You might debubiate! In the work of Zora Neale Hurston and in Harlem Renaissance...