For the tiki just take a solid colored paper cup, found in the party supply section of any superstore, then have the kids decorate it with foamie stickers, markers, ect. I used glue dots for the googly eyes and the crepe paper hair.
To make the crepe paper (party streamers) hula skirt you just cut a long strip of butcher or craft paper. Then take a large hole punch, in this case it was a square, and cut along the strip of paper. Have the kids tread the crepe paper through the holes and with a glue stick glue the crepe paper onto itself. When they are done wrap it around their waste and staple it. You can staple a lei around their waste as well.