Okla. Stat. tit. 18, § 438.11

Any person entitled to notice of a meeting may waive such notice in writing either before or after such meeting. If any such person shall attend such meeting, such attendance shall constitute a waiver of notice of such meeting, unless such person participates therein solely to object to the transaction of any business because the meeting has not been legally called or convened. Laws 1953, p. 487, § 11.