be a material which is readily heated by use of a microwave and retains heat in order to be insertable into the cavity 18 in the beverage container or the insertable substance may simply be a hot liquid heated from any conventional source and used to heat the liquid as shown in the figures the lower end of the insert has a relatively short cylindrical wall 23 terminating in a bottom face 24 that has a number of finger grip depressions 25 therein one or more pins 26 project outwardly from the cylindrical wall and they are positioned to co operate with inclined slots 27 suitably located in the entry portion 19 of the cavity referring to fig5 each of the spaced apart inclined slots 27 have an open entry portion 27 a in the bottom wall 17 of the container and terminate at the other end in a stepped down portion 27 b in use the insert can be taken from a freezer in it 39 s frozen state and inserted into the cavity 18 19 the insert is rotated to align the pins 26 with the notches 27 and inserted into the entry portion thereof rotating the insert a partial turn causes the pins to slid in the inclined slots forcing.