I'll pay that 

Used by Australians to positively affirm a statement/opinion someone makes/has. The saying originates from Australian Rules Football, Australia's national sport, where an umpire "pays" a free kick, a mark (catch from a kick), etc.

P1: Mate, i just don't like meat pies.

P2: That's so unAustralian.

P3: Yeah, i'll pay that.

I'll pay that by Lockstock November 20, 2015

I'll pay that 

I'll give you that.
Granted.

To be dumbfounded by someones comment, then allowing that comment to pass or giving them credit for what they said.

Nick: Help me find a definition for this word!

Jiro: I don't know I'm sleepy.

Nick: I'll pay that.

I'll pay that by Time keeper April 7, 2009