Roleplaying is the act of pretending to be something which you are not. Specifically, roleplaying games are games played where the players take on the roles of specific characters, and describe what they do. Roleplaying games have been around for quite a long time, and range from tactical fantasy combat simulation (such as the rather famous Dungeons and Dragons) to comedy games (such as Paranoia). Roleplaying games exist for pretty much any situation you care to play, and there are some generic systems designed to incorporate any scenario.
Most roleplaying games tend to take place around a table, with the characters existing on paper, or as models on a board. Some roleplaying games are played without any paper at all, with the players just sitting around and talking. These games are commonly referred to as "tabletop" roleplaying games.
LARP (Live action roleplaying game) is a type of roleplaying where instead of recording your character on a sheet of paper, and representing them with a model, or in your imagination, you take on the mantle of your character physically, and act out their actions in real life. This has some advantages and some disadvantages over traditional tabletop roleplaying. Swinging heroically from a chandelier while fighting a horde of screaming harpies might work in your imagination, but actually doing it is another matter. On the other hand, what you do in LARP is a lot more immersive than most tabletop games.
In order to monster, you need to read the System calls page, and the hit system page, which will let you know how to act if someone starts shouting confusing instructions at you. The refs will take you through this when you first arrive, and give you a quick safety talk as well as answering any questions you may have. You'll also want to wear loose, comfortable but plain clothing. Try to avoid anything modern looking - in particular, denim, white trainers and obvious logos can look decidedly out of place. Finally, you might want to read our guide to roleplaying.
In addition to knowing about the calls, you'll need a few extra things to play a character:
As always, email queries downtimes and general musings as to the nature of the multiverse to tt-refs@srcf.ucam.org.