Wiktionary
choose up
vb. (context idiomatic intransitive English) To select, pick.
WordNet
choose up
v. form sides, as for a game
Usage examples of "choose up".
He gave assignments to each of his assistants and allowed them to choose up sides.
And I expect if he's sent the lad to tell me, it means he kens the man who's responsible, and doesna mean to choose up sides wil me against him.
You will come with us and do as we say, or either of us can press one stud on our wrist controllers and you will be shocked at whatever level we choose up to unconsciousness.
Section three was the right of Israel to choose up to one hundred extra targets that the Allied air forces would obliterate.