Last time I went to Mexico I bought some cheap Luchador masks. No idea why, didn't even have a use for them. They ended up staying in my car for months. For what ever reason I put them on all the headrests because it just seemed like the right place to stick them.
Like those crappy masks I bought in Mexico, I don't really see a need for these headphone plugs, but yet I want them. Actually the other day some little piece of crap fell into that little hole and it took me a second to get it out. So maybe I do have a use for these things. You can pick them up here—thanks Japan.