Press space to add rubber bands. The first screen shows how many in this demo. Double click the flag to get it going for the first time and after you break it.
Don't try this at home. I saw a video a year ago about this type of experiment. Wrap several rubber bands around a watermelon. Soon, the pressure from the rubber bands will pierce the rind and the water melon will explode while the bands form a tight rubber ball. It's not so smart to be within close range unless you want to get hit with the pieces that fly out. The video was made by 2 guys. I can't remember what the channel was but search up "slow-mo watermelon explosion" or something similar to that and it may pop up.