With a shortened ''Friends'' season this year (just 18 episodes), who gets to decide how NBC will fill time until the series' final episodes, which the network is saving for April and May? As it turns out, you do. In a joint statement released on Thursday, NBC, ''Friends'' production house Warner Bros. Television, and AOL announced that fans will get to pick six favorite ''Friends'' reruns to air in the show's Thursday slot during March and April. (AOL, Warner Bros. Television, and EW.com are all owned by Time Warner.) Fans can choose from among 40 of the 200-plus episodes from across all 10 seasons, and NBC will count down the six top vote-getters week by week from March 4 until April 8. You can vote until Feb. 1 at AOL Keyword: Friends or at AIM.com. Our personal favorite: the one where Ross and Rachel have a sex-related misunderstanding, which inspires Chandler to make a sarcastic comment.