Vice President Kamala Harris has a nervous laugh that may or may not be the result of a medical condition.
The syndrome, “Pseudobulbar affect (PBA), was suffered by the Joker, played by Joaquin Phoenix in the movie of the same title.

In the film, Phoenix plays Arthur Fleck, a man struggling with inappropriate laughter, similar to the Vice President.

According to the Mayo Clinic, “Pseudobulbar affect is characterized by episodes of sudden uncontrollable and inappropriate laughing or crying.”
Echoing the language on the Joker’s laminated card, PBA can indeed occur in people with brain injuries, stroke, or certain neurological conditions.

Similarly, the Vice President seems to launch into sudden episodes of uncontrollable laughter especially when she is asked a tough question.

Pseudobulbar affect often goes undiagnosed or is mistaken for mood disorders. Once diagnosed, however, pseudobulbar affect can be managed with medication.