Siméon Denis Poisson Moment

Physicist: "Wave theory of light implies there should be a bright spot at the center of a circular shadow? That's absurd!"

*Poisson's spot actually appears in experiments*

Physicist: *spits drink dramatically*

This is the historical physics equivalent of saying "I'll eat my hat if that happens" and then having to grab some ketchup. When Augustin Fresnel proposed his wave theory of light in 1818, Siméon Poisson thought he'd cleverly disproved it by showing the math predicted an impossible bright spot in the middle of a shadow. Then François Arago went and did the experiment... and found the spot. Oops! Nothing like the universe saying "actually, check THIS out" to humble a scientist.