“Hey Ethan, what’re you doing?”
“Oh y’know, just washing my ears.”
I bought these: http://www.trendyhalloween.com/Woochie-Werewolf-Ears-P12867.aspx#.UjCS6cYjLGU last year because the other elf-ears in the store were too short for my liking and it’s a lot easier to go from dark brown to black than pale peach to black.
I mixed a few drops of black acrylic paint into some liquid latex and re-coloured them. A bit of matte finishing spray to take off the rubbery shine (and stickiness) and tada! Drow ears.