A coaster is structured to be coupled to a conventional cup, such as an iced beverage cup, using a conventional cup sleeve. The coaster includes a generally disk shaped base having an outer perimeter. Two or more elongate tethers extend outwardly from the outer perimeter of the base. The coaster assumes a combination-ready configuration with the two or more elongate tethers extending generally upright and outwardly to a same side of the base, in such a way that the coaster fits snugly within a conventional cup sleeve. In a final combination configuration with a cup sleeve, the coaster combines with the cup sleeve to create an insulating and water absorptive coaster and sleeve, frictionally and snugly coupled to the cup in a robust manner to make the coaster highly portable together with the cup and cup sleeve, and configured to collect condensation formed on the exterior surface of the cup.