WITH ONE FROG YOU CAN:
Hop it into a saucer
Hop it over a knife or fork
Hop it into a cup or bowl
WITH TWO OR MORE FROGS YOU CAN:
Have a distance competition
Have a saucer, bowl, or cup competition
Have a knife-crossing competition
WITH A HUNDRED FROGS YOU CAN:
Re-enact the Biblical plague from Exodus!
Feel free to suggest more frog games in the comments below.