party·er, parti·er n.
Usage Note: Party is unexceptionable when used to refer to a participant in a social arrangement, as in She was not named as a party in the conspiracy. It is this sense that underlies the legal use of the term, as when one speaks of the parties to a contract. The legal use has in turn led to the presence of the word in many fixed expressions, such as injured party and third party. But party is also widely used as a general substitute for person, as in Would all parties who left packages at the desk please reclaim them. This usage has been established for many centuries, but in the Victorian era it came to be associated with the language of the semieducated and it has been the subject of many later criticisms. This use of party may have been reinforced in the 20th century by its adoption by telephone operators. In other contexts, when used in earnest, it may be perceived as a superfluous variant for person. But the jocular use of the term is well established, particularly in references such as a wise old party.
http://www.thefreedictionary.com/partyer
par·ty·er [pahr-tee-er] Show IPA
noun
a person who parties, especially regularly or habitually: New Year's Eve always brings out the partyers.
http://dictionary.reference.com/browse/partyer
