keep (one's) chair
obsolete To remain seated (in one's chair). The ship pitched back and forth so violently in the storm that it was impossible to keep one's chair. I have asked the audience to keep their chairs until the very end of the performance.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
keep one's chairand keep one's seat
Fig. to stay seated; to remain in one's chair or place. That's all right. Keep your chair. I'll find my own way out. Please keep your seats until after the question-and-answer period.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.