Samarian sunset

From Memory Alpha, the free Star Trek reference.

The Samarian sunset is a beverage which is initially clear, but when the rim of the glass is tapped sharply, an orange color appears in the liquid and streams out until the entire drink turns color.

In 2368, Data made Deanna Troi a Samarian sunset in the traditional style, as per their bet after he lost a game of three-dimensional chess to her. (TNG: "Conundrum")

Samarian sunsets were a favored drink of Cardassian professor Natima Lang, who stopped drinking them after she and Quark had a falling-out, since they reminded her of him. (DS9: "Profit and Loss")