To be essentially fucking with someone or to be condescending to someone by implying that they are
stupid.
Refers to when someone says "Don't
piss in my
pocket and tell me its raining, jerky..."
Tom: "Thanks for the CD, I
like rap music.."
Sue: "Are you taking a
piss?"
Tom: "No, not at all. I really do like this CD. Thanks
a bunch...really."