Sexual jokes can be very funny if told correctly, in a non-discriminating fashion, in the right context to the right people. That also means that they can backfire horribly, especially if random people around. To me, thats not even a question of sexism, many feel uncomfortable if that happens, regardless of gender.
An open space conference certainly never is the right place. Also, cheap jokes about "dongles" are never worth it... please, keep it classy...
Honestly, I wish they were off the table regardless of who is in attendance. They're rarely funny, and they add nothing to the conversation.