You’ll probably think it tastes better. According to this study highlighted in Popular Science:
In what may have been the easiest volunteer experiment ever, 57 people had to drink hot chocolate served in four different types of cups. They were all plastic and the same size, but were either white, cream, red or orange with white inside. The tasters reported the chocolate tasted better in the cream-colored and orange cups.
The color had nothing to do with this difference, neither physically nor chemically, but apparently the drinkers’ brains thought they detected a difference, according to Betina Piqueras-Fiszman, a researcher at the Polytechnic University of Valencia in Spain. The study references other similar findings–like the perception that yellow packaging improves lemon flavor, or that blue drinks appear to be more thirst-quenching than red ones.
More here.