I have been asked to come with a display for bonfire night but I have to admit i'm kinda stumped.  Anyone got any ideas??

I'm a bit stumped too. Maybe a guy, or a sparkler?

Not sure how much time you want to put into it.  How about a woven marshmallow (350s), with a malevolent face that has a person on a stick?
Wow, if I ever have time (unlikey) I'll make that one for fun!
Post pictures of whatever you decide.