"buckup" was a term Texans (maybe other Southerners) used to mean "find your inner strength to deal with a problem or situation." As a child when I had difficulties with bullies or any other hard situation I heard the term used. I could see Jim Bowie or Colonel Travis at the Alamo saying to their men as they faced certain defeat and death "Buckup!"
Definition #2 for "buckup"
The numerical value of buckup in Chaldean Numerology is: 9