Down
American SlangDefinition
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."