Halloween Advice

A couple of days ago the boys came home from school with their very first Halloween Party invitation, for people who don't know Halloween is not something that is a big deal over here in Sweden, and personally i don't think it's such a big thing in the UK where i come from. Sure we get the odd kid or two coming around shouting "Trick Or Treat" but that is about as far as it goes.

I know that in places like the US, Halloween is a gigantic holiday and they take it to the fullest, but again not here, so when the boys came home with this invitation myself and Marie were kind of baffled. 

Of course the first question that left Marie's mouth was "Errm what should we dress them up as?". But if i'm totally honest i have no idea because it's not something i have ever been into, i did go to the odd school Halloween party when i was a kid growing up but i never ever dressed up because i just found it silly, so i used to put my own cloths on and when asked "What are you meant to be?" my simple reply was "A homicidal maniac, since they all dress like normal people" If you didn't already gather i got this from i believe the original Adams Family movie.

So i am appealing to all my reader's out their. What should we dress our twin boys up as? I'm hoping that you all have some idea's because as i said above i really have no idea about this type of thing, so any help would really be appreciated.
Keep in mind that they are both only 6 years old, so nothing to extravagant.

But until next time, i shall bid you all farewell...