A social meeting or gathering that is largely, in the view of the person, is fake or under false pretense, the person generally is not looking forward to it, or the person must feign interest in. It would generally otherwise be a happy event to most attendees. Used sarcastically.
"Human Resources is hosting a weenie rub on Friday to celebrate the start of spring."
"I've got to go to some weenie rub my wife's boss is having at his house."
"We're going to kick it this weekend - we may go to some weenie rub down at the museum to benefit diabetes"