Does this make sense? Your tongue can stick to a flagpole because the freezing point of your saliva is higher than the melting point of the ice crystals on the pole.
Interesting question! If you've ever had your fingers freeze to ice cubes you know that this can happen even without saliva involoved. It's more likely that the freezing temperature of saliva is the same or slightly less than the melting temperature of ice crystals on the metal pole. The freezing point of a substance is the same as its melting point. Both the ice crystals and saliva are predominantly water. Pure water melts and freezes at 0º C. If water has anything dissolved in it its melting point will be lowered. Saliva has some dissolved solutes so its freezing temperature is a little below that of pure water, not higher.
If someone were to lick the ice crystals on metal that's below 0ºC the heat from the tongue might begin to melt the ice but the melted ice and saliva would quickly freeze because the metal pole, being colder than the tongue, would absorb the heat. Heat travels from where there's more to where there's less until thermal equilibrium is established, which means that the temperatures are equalized. Metal is a very good conductor of heat. The heat entering the metal from the warm tongue moves through out the flagpole. Since the flagpole is very large compared to the tongue it's unlikely that thermal equilibrium will be reached. Heat will continue to be transferred from the tongue to the flagpole.
Should this unfortunate event occur, pouring warm water over the area where the tongue is adhered to the pole should melt the ice long enough for the tongue to be quickly removed.