"3rd" is just the name of the single; there is no song with that title, like 1st and 2nd. Therefore, it is hard to know whether 3rd should be classified as an EP or a regular single. EPs usually have more than two songs on them, but, on the other hand, "3rd" is no title of any songs by the band.
It was the last single to be released from the album Peep and features the tracks "Ghostbusters" and "Fool". Both of these tracks are taken from the album Peep. It went #8 on the Finnish Singles Chart later that year.