There are many alternatives to icecubes available.
Today’s invention is one such approach. A novelty item (such as a shark’s fin or a sinking ship) is moulded in glass and has embedded within it an iron core.
This allows the ‘cube’ to be held firmly in place in a conventional glass by an external magnetic disc applied to the base.
The novelty cube would be chilled in a freezer before use and allow the glass to be used without diluting or contaminating the drink (as may happen if you use eg cold stones).
There would be no possibility that the cubes will interfere with eg straws or come out -until removed by hand for cleaning purposes.
If you want eg mulled wine which stays warm, heat the cube first. A more advanced version might have a ‘cube’ containing an led which lights up in response to the magnetic field from below.