Today’s invention is a way to make use of the dribbles from a cup or glass.
Each drinking vessel at a party would have a press-on disc attached to its base. This would have machined into its underside a series of channels in the shape of a logo, a celebratory message or an advert.

The disc would fit neatly (in only one rotational position) within a coaster which forms part of the kit. When any dribbles flow onto the base of the glass, they fill the engraved advert (by surface tension) and magically leave a message on the coaster (or any other surface the glass is set upon).