E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
When members of the House of Commons and other debaters call out Chair, they mean that the chairman is not properly supported, and his words not obeyed as they ought to be. Another form of the same expression is, Pray support the chair.
Groaning chair. The chair in which a woman is confined or sits afterwards to receive congratulations. Similarly groaning cake and groaning cheese are the cake and cheese which used to be provided in Goose month.