TL;DR: Go for it, but please call your conference something else.
From time to time, people ask us if it's okay with us if they organize their own !!Con-like conference. We're thrilled that you like the idea of !!Con enough to want to organize your own !!Con-like event, and we're totally okay with that, with the following caveats:
- don't call your conference "!!Con" (or use our logo or other branding), and
- don't claim any official affiliation with !!Con.
(We first stated this policy in July 2014.)
It is, of course, perfectly fine (but not required) to say that your event was inspired by !!Con. Two recent examples of similarly-themed conferences are EnthusiastiCon, held in Berlin in June 2015, and Curly Braces, to be held in Atlanta in November 2015.
!!Con is a conference of ten-minute talks about the joy, excitement, and surprise of programming, but there are also a lot of other things that we do that make !!Con what it is: anonymized talk proposals, real-time captioning, pay-what-you-want admission, no Q&A, and so on. You are, of course, not obligated to do any of these things at your own conference, but we think they make !!Con better, and we hope that you consider them!