Ad ridiculum

X is amusing, absurd. Therefore it is false.

Mock the other person's claim and argument. Make fun of it. Get people to laugh at it.

Alternatively, mock the alternatives that they might choose, giving them only one option that you have not mocked.

Ridiculing something is to place it at a lower social position. If a person is associated with that thing, then they, too, are moved to that lower position. When others see a person in a lower social position, they will not associate themselves with that person, for fear of being dragged down to that position. The original person knows this, and will seek to avoid loss of social status.

The ridiculed thing is thus poisoned and made undesirable, and people will distance themselves from it.