Smack the hoshanos
קוֹל מְבַשֵּׂר מְבַשֵּׂר וְאוֹמֵר
Press and hold to wind up, let go to smack
0smacks
0leaves left
–fewest smacks to bare
Hold longer for a harder smack. The minhag is five times on the floor. After that, see how few smacks it takes to knock every last leaf off.