80's New Zealand slang.
Means "psyche" or "burrrrn"
Can be shortened to just "sold".
Literal meaning would be "I sold you on my trick".
get someone to get something for you.
sam tells dom to get him a beer.
dom gives sam a beer.
sam sold dom for a beer.
sam: i sold you for a beer
or you get someone to buy something for you
you sold them for whatever they bought you.
"yo sam just sold you for a beer"