(definition) by Vulgar Tongue 1811 Tue May 03 2005 at 23:25:38
up to their gossip

To be a match for one who attempts to cheat or deceive; to be on a footing, or in the secret.
I'll be up with him ; I will repay him in kind.

The 1811 Dictionary of the Vulgar Tongue.

I like it!