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.
yapc.org
The silly acronym comes from Perl's (and indeed Hacker Cultures) long history of them, such as the well-known "JAPH".