He's 81, after all

My father. He's 81. Nearly 82. And sometimes he says things that don't seem to make any sense, and that flicker goes through my mind. Could he be going senile?

Today, I told him I had unexpectedly received $40 in gift cards from the grocery for pretty much just doing my basic shopping, and he chortled, "Egg in your beer!" And I thought, "What? What kind of fool malarkey is that?!?! Poor Daddy."

egg in your beer
idiom
A bonus, something for nothing. This expression dates from about 1940 and became widespread during World War II. The origin is unknown, since adding egg to beer does not improve the taste.
"egg in your beer." The American Heritage® Dictionary of Idioms. Houghton Mifflin Company, 1992. Answers.com 22 May. 2006. http://www.answers.com/topic/egg-in-your-beer

Poor Daddy nothing.