So I'm not a baseball player, but I do perform some great work in the batting cage. It's a word that I made up on the spot that accidentally stuck even though I'm 100% sure there's a better metaphor somehere.
The Batting Cage
Definition
Batting Cage Idea: An idea that is not meant to be a proposed solution, but rather meant to inform the brainstorm session in case there's a good idea that can come from it.
(Why not just brainstorm? Why the separate term?)
To be totally transparent about this, I think it's mostly psychological - I feel that a lot of the time people are scared of saying their idea because it's obviously not going to be the solution needed, and people are just going to judge them for saying a 'waste of time' proposal. The "batting cage" disclaimer lets your idea be heard for the sake of inspiration instead of for the sake of evaluation.
Example
"Okay, so what other levels could we make for our protagonist 'MatchEars'? Other than avoiding methane houses?"
"More fuse lighting? A lamp level?"
"I feel like it'll get old if we do that again, and the paper lamp level sounds already a lot like the hot air balloon level"
"OK, batting cage: underwater level. Or something with water, I feel a nug there."
"Oh, what about a level where it periodically rains, and he needs to hide underneath awnings?"
This isn't to say that MatchEars should ever be made into a game, or that any of the above ideas are good. But this should hopefully exemplify how a batting cage idea can be useful to conversation when with people who can appropriately spring from it.
Benefits
1) The main reason you do this is to inspire others. If someone else had a half-idea but were missing a piece, now you'll maybe indirectly deliver that piece!
2) If you know there's something good in the idea, but you're not sure how it can be shaped, it shifts the conversation away from why it's bad (because what a waste of time -- you already know it's bad) and towards how it can maybe be good.
3) Sometimes it actually is a great solution, and your doubts were just because of how buckwild an idea it was. The "batting cage" disclaimer gives you the courage to say your ideas, and it happens more often than you'd think that a batting cage idea is actually the perfect solution as-is.
Drawbacks
1) If people don't know what "batting cage" means, then they'll just critique your idea and not realize that you weren't doing a proposal in the first place. It ends up wasting time.
2) It gets easy to just slam "batting cage" in front of all your ideas as a means to protect yourself from critique -- don't do that! It'll lose its 'power' (so to speak) if you aren't honest with yourself when you're actually giving a proposal.
3) At some point, people need to start synthesizing all these ideas into real proposals. A team's workflow is best when there's a good group of people who are actually capable of drawing inspiration from what you're saying.
Give it a shot!