I've been to meetups where this happened and while it isn't ideal I've usually received a warning that I should show up early. I was talking more about telling

I've been to meetups where this happened and while it isn't ideal I've usually received a warning that I should show up early. I was talking more about telling somebody already inside that they have to leave because they were randomly selected (and using the police to force the issue if needed), similar to what recently happened with United.