The Tesla chief -- and now, the Twitter board member -- floated a somewhat kooky idea this weekend about what to do with the social media company's San Francisco headquarters ... namely, whether he oughta help turn it into a place where the needy can come and crash.

He posed it as a question in a poll, writing ... "Convert Twitter SF HQ to homeless shelter since no one shows up anyway," with a simple "Y" or "N" response. As of this writing, upwards of 1.7 million have responded, and they're mostly saying ... do it, dude.

Welp, it sounds like the former Amazon honcho -- and currently the 2nd richest guy in the world, behind Elon -- heard about his tech bro's dilemma ... and offered some advice.

Jeff responded, "Or do portion. Worked out great and makes it easy for employees who want to volunteer." He attached a link to an article that details exactly what he's referencing ... apparently, Amazon's Seattle HQ did exactly what Elon's proposing a couple of years back.

The Amazon shelter -- which actually lies within the Seattle campus and is attached to one of their big offices there -- is called Mary’s Place Family Center in The Regrade ... and it's a whopping 8 floors, spanning 63,000 square feet and with the capacity to house around 200 people a night.

Amazon teamed up with MP to get this place going amid the early days of the pandemic, and by all accounts ... it's been a godsend to the community. The digs ain't bad either.