@ricci My fav conference accidental Mashup was when an Anniversary Star Trek Conference was happening at London Excel center at the same time as:

An International meeting of Senior Hassidic Jews
And
The European Meetup for ZUMBA Instructor - Trainers
And
The National Firefighters Training Seminar

My favourite memory is seeing a Fully Uniformed Firefighter, holding a neon clad Zumba instructor over his head while she was Planking, while a Klingon & Hassidic elder looked on in admiration