You could make everyone go in fancy dress, or a mask, or they all have to wear the same colour eg. White, then you make sure that your DH is wearing black that night so he stands out.
You could get printed t.shirts for everyone to wear saying something like - I'm with the 30yr old.
Everyone could wear outrageous hats.
You could make all the ladies wear colourful feathered bowers, & the men bright funky ties.
There's nothing more funny then the ordinary guy that stands out at a funky party.