You can freeze anything in an ice cube tray
and then float it in a drink.
Fruit is an excellent candidate, any kind, pureed and strained (optional – I don’t mind seeds) will make a lovely addition to a summer drink. Or herbal or regular tea.
If you want to make it an adult beverage you even top it off with a little vodka, rum or gin. Doesn’t a watermelon screwdriver sound good?