I went to the doctor and told him I kept forgetting things.

This joke tickles our funny bone through a brilliant blend of absurdity and irony. The humor stems from the doctor's completely unhelpful, even counterintuitive, advice. When a patient complains of forgetting things, the expectation is for a medical professional to offer a solution, a diagnosis, or at least a practical suggestion. Instead, the doctor's instruction to "keep doing what you're doing" and "come back if you remembered" directly plays into, and even exacerbates, the patient's problem, creating a delightfully illogical scenario.

The real-world context grounding this joke is the common human experience of memory lapses and the trust we place in doctors to help us with our ailments. Everyone has forgotten something important at one time or another, making the patient's predicament relatable. Doctors are seen as figures of knowledge and healing, so to have one respond with such a circular and unhelpful suggestion is a comedic inversion of our expectations, highlighting the frustrating nature of memory issues in a lighthearted way. It's a clever twist on a very ordinary medical consultation.