A bird costume would be easy, and lots of birds are yellow.
any costume to do with world championship
One should wear a maid sama costume and a cute wig that goes with it but not a hood.
If you are going door to door or a costume party-yes.
If an individual feels it is right to wear a certain costume, than he or she can. There should be no limitations to what an adult should wear as far as costumes are concerned. For a general idea of what an age-appropriate adult costume looks like, though, check out this site: http://kccbigcountry.hubpages.com/hub/Halloween-Costume-Ideas-to-Wear-to-Work
a horse costume.
a ghost costume or a ninja
The costume your teacher gives you!
whoopie cushion costume. be warned some kids might try to sit on you but that's okay
I think you should wear anything maroon under a yellow jersey.
Briefs
A barney the dinosaur costume.
the one made out of meat!