This is a 'mangled metaphor'. It mixes up 3 idioms:

Piss on my leg and tell me it's raining
Piss on one's chips
Piss and vinegar

To deliberately and painstakingly go out of one's way to ruin a friend's chances of success. Usually done jokingly with reference to the opposite sex.
No way do I want you as my wingman. You would piss on my chips and tell me it's vinegar.
by fuguez September 26, 2009
Get the piss on my chips and tell me it's vinegar. mug.