When an elderly person, such as your grandfather, complains incessantly about nothing.

When an elderly person is using the restroom.

Esp. when he/she is taking a long time.

1)Well organized gang of shakedown artists running a protection racket, extorting usurious payoffs from honest businesses using the tactical codewords 'Senior's Discount'. Using tactics not dissimilar to those of organized crime, differing only in its blatant daylight robbery nature and its quasi-legitimacy as an NGO.
2) The Political wing of the notorious Grey Panthers.

The voice of senile people!

How old people get things cheaper.

AARP is for the American Association of Revolution Pilots, and to recognize all of those aviators who risked their lives flying during the Revolutionary War. It's an organization that came out of hiding on July 4, 2019 when our sitting President flubbed yet another speech, in which he referred to the Revolutionary War, in June of 1775, "Our Army manned the air, it rammed the ramparts, it took over the airports, it did everything it had to do, and at Fort McHenry, under the rocket’s red glare it had nothing but victory. And when dawn came, their star-spangled banner waved defiant."

Getting old, (Derived from the organization that caters to seniors)