Re enact different scenes from movies, really loudly.
I suggest any of the well known scenes from the movie "Yolngu Boy" (not a very well known movie but would be good to act out, especially at the end, yell out "BOTJ, WAKE UP, WAKE UP BOTJ" or "GIVE ME SMOKES" or "I DARE YA"
Build a miniature roller coaster in the store with a cart that can be rode and offer free rides for everyone. Give them a stick so they can poke the wares while riding.