a polite way of saying...

[justsomeone]

Hello. Im new to engligh.
And I wonder how to say "Go f**k yourself" in a polite manner, so that people dont take it as offence ?
I often hear this phrase, but i think its kinda rude. What you think?
Thanx.

[Raymott]

Hello. Im new to engligh.
And I wonder how to say "Go f**k yourself" in a polite manner, so that people dont take it as offence ?
I often hear this phrase, but i think its kinda rude. What you think?
Thanx.

It's more than 'kinda rude'. It's totally unacceptable, unless you never want to see that person again, and you don't care what bystanders think of you. (Of course, people who very familar with each other might say it.)
"Go [and] jump in the lake" is probably the classical phrase, but it's outdated, and rather lame.
It also depends on exactly what your meaning is. It can be a general insult, indicating that you don't agree with that person's opinion, and you want them to go away.

Generally, some variant with "off" would do.
"Rack off (tame); piss off, bugger off (stronger, mild swearing), f**k off (also generally unacceptable, but less extreme than your example).
...
Maybe someone who uses these terms more often can suggest some better phrases.

[Vidor]

No, you cannot express that statement politely. You can be less vulgar, but you can't be polite.