Two of my favourites:

You couldn't organise a piss-up in a brewery.

or

You couldn't getta root in whorehouse with a fist full of fifties!



edit: Typos

[Updated on: Fri, 06 August 2004 05:30]

I heard that your parents had an adoption, now I see that's true.

You're a douche bag....

You arent worth the c*** juice i can squeeze out of an old whores tampon

Savage (^)

[Updated on: Fri, 06 August 2004 08:12]

Wow, with a face like that you better be charming.

There's a few others, but the best ones are always the simple ones delivered properly, ie with a big smile, a hand on the shoulder, or sitting down and having a serious talk to them.
These ones work with taht formula:
Good one mate but... you're a fuckhead!
Dude... you are really really ugly. < favourite
(serious talk) Look, wake up to yourself. You're a joke, always have been, always will be. So just give up, ok?
If they tell a joke or something, ha ha, ahhh, ha... no.
Or just plain ignore them, look at your watch/phone when they say something, and just go, "Uh huh, yep, yeah, how bout that, wasn't aht great?"
I don't know, denials involve creativity, plain insults involve opportunity.

Oh, plus... "I've never had sex with your mum. The line was too long..."

[Updated on: Fri, 06 August 2004 11:19]

[Updated on: Fri, 06 August 2004 22:21]

Quote:

"you want a match? - I've got a match, my arse and your face"

How's this:
"You're not exactly a rose, but you know that potato does bloom too."

or
"You must have been birth arse first and I bet that not even your mum didnt notice the difference"

This is common utterance/answer to insult In Finland. For example if some yells to you that "you fnking shtty gay" or "you ars€hole wank€r"
you say that "your mum was when she got you...
...and your father still is!"

[Updated on: Tue, 10 August 2004 13:53]