Another term that may be more familiar is "ice breaker". The senior person offers up an idea to get the ball rolling. It shouldn't be too complex, it shouldn't sound like the way to go. It's just something to help make other people more comfortable participating, especially people junior to them. It may even be a dumb idea, getting some laughs and breaking the tension.
The value is creating space where the bar for acceptable ideas is so low that people don't self-censor.