Another thought I had reading this thread...
FOUR people jumped on you? And physically held you down?
I think in that case, it's not a question of etiquette, but of safety - they've just physically attacked you. If that ever happened again, and I were in your shoes? I'd turn into a feral wildcat - flail, punch, scratch, jab with elbow, jab with knee, bite...whatever it took. And then when they let go? I would go with the "how dare you." Because that is NOT funny and, in my world at least, NOT acceptable.
(Heck, my mom gave me permission to do all that if someone *tickled* me and wouldn't listen to 'stop'!)