If you're new to the Roswell web, you might be wondering what people are talking about when they throw around words like "shipper", "Cliffhanger" and "Hussy". You might be wondering how people even get these ideas into their heads - mostly it's due to the creative minds in the wonderful world of fan fiction! Here's a primer:

NOTE: shipper = in favor of a romantic/sexual relationship between characters

Applesaucer - Shiri Appleby (Liz) fan
BASST - Brothers and Sisters Sleeping Together. (See an anti-BASST site here)
Behrian - Jason Behr (Max) fan
Blonde Ambition - Maria/Isabel/Tess shippers
Blonde Attitude - Maria/Isabel shippers
Bob - Max's Jeep
Bobber - fan of Max's Jeep
Boomer - Back Off Our Michael-er
Candygirl - Michael/Maria shipper. Collectively named Candyclan. Comes from M&Ms... the candy. Get it?
Chads - Investigators and discussors of plotholes and continuity issues on Roswell
Cheerleader - Kyle fan
Cliffhanger - Michael/Isabel shipper. Comes from the dreams Mike and Iz had of making out on the cliffs.
Copycats - Liz/Ava shippers
Cowgirl - Kyle fan
Darth - Refers to Darth Katims, also known as Jason Katims, the executive producer of Roswell
Death Trapper - Fans of Max's Jeep, Bob. Also Jeep/Jetta shippers (hey, it's all in good fun!)
Donor - Alex fan
Double Dipper - Max/Liz/Zan shipper
Dreamgirl - Max/Liz shipper. Also casually referred to as a Dreamer. Comes from Max calling Liz his dreamgirl.
Fan Forum - Unofficial main message boards on a variety of shows; they also run Crashdown.com. Check it out.
Fehrian - Brendan Fehr (Michael) fan
Fifth Wheeler - Tess/Alex shipper
Friendshipper - fans of the friendship between Liz, Maria and Alex
Genie - an early name for Maria's Jetta. Comes from Maria singing "Genie in a Bottle" while driving.
Granilith - That weird thing behind the pod chamber that the Skins want to get their hands on. Can regenerate the Skins' bodies; also can be used as a time travel device.
Groupies - Maria/Alex shippers
Ground Zeroer - Max/Maria shipper (if anyone knows why they're called this, drop me a line!)
Healer - Max fan
Holo-mom - The holographic image of Max and Isabel's mother as seen in Destiny
Hussy - Tess fan
Hussylovers - Tess/Courtney
Ice Cube - Courtney/Isabel shipper
InCrowder - Kyle/Isabel shipper
Knockouts - Alex/Michael shippers
Lamptrimmer - Kyle/Tess shipper
Lifesaver - Maria/Tess shipper
Lizizards - Liz/Isabel shippers
LMG - Little Match Girl. Fans of Brendan Fehr's new 'do who think he looks like Rob Thomas of Matchbox 20.
Lolly - Michael/Brendan Fehr fan
Loner - person with no shipper preferences
Loyalist - Liz/Kyle shipper
LPGA - Liz Parker Guardian Angels
MALSS - Michael and Liz Separation Society
Mental Vibrator - Michael/Tess shipper
Mikey's Angels - Courtney/Maria shippers
Mind Warper - Isabel/Tess shipper
Mirror - when used before any of these ships, implies a Dupe ship
Outsiders - Max/Isabel shippers
Panty Brigade - Max/Kyle shippers
Past Indiscretions - Isabel/Nicholas shippers
Peanut M&M - Max/Michael shipper
Pepperjacker - Maria/Brody shipper
Pimpette - Rath (Dupe Michael) fans
Pixie Chick - Maria fan
Plasmatics - Alex/Max shippers
Pod Squad - Max, Michael, Isabel, sometimes Tess
Podfather - Sheriff Valenti fan
Polarist - Michael/Liz shipper
Psychokiller - person who likes angsty fanfics with rape, violence and death
RAGE - Roswellians Against Glorified Extras. An anti-Tess group.
Rebel - Max/Tess shipper
Rebound Team - Kyle/Maria shipper
Rebounder - Kyle/Tess shipper (also called Lamptrimmer)
Reflectionist - Isabel/Lonnie shipper
Remedialist - Kyle/Maria shipper
Roswell High - The name of the book series by Melinda Metz that the show is based on. Also what the show is called in Europe.
Second Generation - Kyle/Maria shipper
Shipwrecker - Max/Tess shipper
Snake Charmer - Courtney fan
Spoilers - advance rumors and news about plot developments on the show. Not everyone wants to know about them, hence the need to be discreet when discussing them
Stargazer - Alex/Isabel shipper. Comes from Into the Woods, when the two gazed at the stars together.
Stimulator - Michael/Courtney shipper
Street Walking Soul Mate - Michael/Rath/Maria shipper
SUMMIT - Smarten Up Michael, Maria is There (I love it!)
Tic-Tac - the shapeshifter who ate mints after he shape shifted. Often referred to as "tic-tac" when people discuss whether he is the same person as Nasedo
TPTB - The Powers That Be (the writers, directors and producers). Also known by the disgruntled as TPTS or The Powers That Suck
Triple A - fan of Brendan/Michael's arms
Truckstopper - Zan (Dupe Max) fan
UC - unconventional; basically any 'ship other than Max/Liz, Michael/Maria, Alex/Isabel, Jim/Amy
Untuckable - Sheriff Valenti/Amy Deluca (also called Pietaster. By me anyway.) Comes from the scene where Liz and Maria come home to find Amy and the Sheriff looking a little...untucked.
Valentines - fans of the Valenti boys, Jim and Kyle
Vigilante Girls - A group of militant anti-Rebel Dreamgirls (More info here)
Waitresses - Liz/Maria shippers
Wild One - Isabel fan

Please let me know if I left anything out!