Definition

Down: slang for being ready and willing to participate; in agreement; loyal/supportive or aligned with a person, cause, or scene; sometimes indicating someone is “cool” or authentically connected.

Examples

"I’m down to hit that pop-up after work if you’re going."

"She’s down with the union and shows up at every rally."

"He’s been down with the underground hip-hop scene for years, so people know he’s legit."