Easiest cover songs

Sorry if this isn't the place for this, but my band is playing a show tomorrow night (we're kinda indie rock/shoegaze/dream pop/post rock) and we were just told by the promoter that we're headlining the show. We typically only play our 5 original songs, but since we're headlining we feel like we need to extend our set. Any ideas for some quick and easy to learn good songs that we could try to jam out at practice tonight?