What it means
Used to insist you’re telling the truth, basically I swear on my life. You’ll hear it when someone’s backing their story, or when a mate challenges you to prove it: Swear down? It’s strong but everyday, especially in youth chat, and it can shut down accusations fast. If you swear down and you’re lying, you look like a proper mug.
Usage examples
"Swear down, I clocked him on the Tube with a parrot on his shoulder, like it was normal, just tapping in at Oxford Circus."
"Swear down, I left the keys on the table, I didn't touch your bag at all."
"He told me he'd pay me back, swear down, and then blocked my number."
Where it comes from
Comes from swearing on something to prove you mean it, with down adding the weight, as if pressing your word into the ground. British youth slang turned it into a quick way to insist you are telling the truth, or to dare a mate to prove theirs.
Other ways to say it
Editors of this term
Your vote counts
Is this real street talk or have we lost the plot? Cast your vote.