Yet Another Perl Conference.
Gathering(s) focused on the programming Language of All Love and All Joy that is Perl
To plagiarize the web site:
The Yet Another Perl Conferences (YAPCs) are grassroots symposia on the Perl programming language under the auspices of the Yet Another Society (YAS), a non-profit, 501(3)(c) corporation for the advancement of collaborative efforts in computer and information sciences.
The silly acronym comes from Perl's (and indeed Hacker Cultures) long history of them, such as the well-known "JAPH".