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."