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."
by Christophe Graham July 6, 2006
Phrase used it the UK to describe the action of taking advantage of the situation, in particular at work. Basically putting the least amount of work possible without getting sacked. The UK English equivalent of mailing it in in US English.
Q: Where is that damn capacity report, Tara should've been done 2 weeks ago?
A: Tara is taking a piss.
by Call Me Ishmael May 25, 2007
Phrase used it the UK to describe the action of taking advantage of the situation. The UK English equivalent of "mailing it in" in US English.
Q: Where is that damn capacity report, Tara should've been done 2 weeks ago?
A: I guess Tara is taking a piss.
by Call Me Ishmael May 9, 2007
Making fun of something or someone
Hey, Jim, you're fat.
No, I'm not!
Naw, you're not really fat; I was just taking the piss.
by mapleLeaf October 21, 2003
To rile, mock, or be a jerk to another person whether or not the person is joking or being serious.
I know what I am so don't take the piss.
Don't worry about him hes just taking the piss.
by nyqs81 September 21, 2005