I am searching for origins of the term "Texas Shootouts" as used in
buy-sell agreements.  A Texas Shootout is a type of buy-sell agreement
that partners, for instance, use to exit a partnership.  Shootouts
work in roughly the following way: in a two-person 50-50 partnership,
the first partner names a price for half of the partnership and the
second partner decides whether to pay that price to the first partner
(i.e., buy out the first partner) or be paid that price by the first
partner (i.e., be bought out by the first partner).

The same arrangement is also called "Russian Roulette."