God, I haven't done Halloween in years. I just pass out candy, now. "Old guy in the big dark house" is scarey enough, I suppose.
But when I was in college, we went for puns at the halloween parties. One year I had a cross between Charlie Chaplin and Emmet Kelly going, but with horns on the derby and a tail made from a stocking leg with a fuzzy tuft coming out from under the tailcoat. I was a bum steer.
One friend was a furry with a syringe on top (spoonerize it).
There was the Celt, all in blue body paint and a loincloth, with a sack of treasure - he was the "Wode warrior from beyond plundered Rome". That one was a stretch...
And the guy in fatigues, with the crocheted afgans strapped like bandoliers across his shoulders, and a toy rifle. The Afghan freedom fighter. It was the 80's...
One year I dressed up as Pinnochio, with vampire punctures on my neck. My girlfriend (now wife) dressed as a female vampire, and we replaced her fangs with little twist drill bits.
She was a sapsucker...
God, there were so many more. The Freudian slip, the memory jogger, the Gypsie Rosalie, ...
There was the John Wayne lookalike. With vampire fangs. His line was, "You heard of The Duke? Well, [smile, show fangs] I'm the Count!"
Get creative, guys. It doesn't take much. If I can find a pic of my greatest costume, from grad school, I'll post it.