In student groups it is often a student member of the leadership team or someone that the leadership team is training. Organizing Localhost events is a great way to teach new team members the basic mechanics of organizing an event (coordinating with MLH, finding a venue, marketing the event, preparing to present, handling day-of logistics, etc).
Sometimes the club is also responsible for the Hackathon, but that’s not always the case. It’s more common for their to be overlap on the team when the community is new or small.
@jamie may have some other thoughts too.
Slideshow Karaoke is a game where volunteers from the audience come up on stage and have 3 minutes to make a presentation. The catch is that they’ve never seen the slides before and don’t know what the topic is in advance! The audience yells out topic recommendations and the MC finds a relevant slide deck on the internet. Some of my favorite topics are things like the history of the Universe, Disney movies, any animal, a summary of Anna Karenina, etc.