No, it’s from Charles Dickens.
Yes, there is humour about old overweight men getting outraged and red in the face, but the definition is from the book Nicholas Nickelby.
The time had been, when this burst of enthusiasm would have been cheered to the very echo; but now, the deputation received it with chilling coldness. The general impression seemed to be, that as an explanation of Mr. Gregsbury’s political conduct, it did not enter quite enough into detail; and one gentleman in the rear did not scruple to remark aloud, that, for his purpose, it savoured rather too much of a 'gammon' tendency.
The meaning of that term—gammon,' said Mr. Gregsbury, 'is unknown to me. If it means that I grow a little too fervid, or perhaps even hyperbolical, in extolling my native land, I admit the full justice of the remark. I am proud of this free and happy country. My form dilates, my eye glistens, my breast heaves, my heart swells, my bosom burns, when I call to mind her greatness and her glory
I rather like the idea of a hyperbolical gammon, eyes glistening etc.