Now this is an awesome prank!

That was an awesome prank but there is a teachable moment included too.  Did you notice the grandma yelling "WTF are you doing"?  That is a factor that has to be considered if you ever have to defend yourself in a public setting.  No matter how justified you are there will be people that are so "frightened" by violence that they will blame you as well as the actual attacker.

I've heard stories of bystanders grabbing weapons because they didn't want to see violence.  Things might have changed today but I don't believe it has.

You heard it here first.