This is another “pointess but cool” drinking gadget, the color changing margarita glass.
Each margarita glass can be lit up in 1 of 8 colors, to change the color (or turn the glass off) simple flick a switch at the base of the glass (you may want to do this when the glass is empty rather than just before pouring the contents on the floor).
The color changing LED margarita glass is available from Lighting for the Home for $7.99.