Okla. Stat. tit. 15, § 15-106: Good consideration defined

Any benefit conferred, or agreed to be conferred upon the

promisor, by any other person, to which the promisor is not lawfully

entitled, or any prejudice suffered or agreed to be suffered by such

person, other than such as he is at the time of consent lawfully

bound to suffer, as an inducement to the promisor, is a good

consideration for a promise.