Well generally asking some one to stop talking is rude. But shut up is the rudest way to say it. so no, dont say that. Usually if you want them to stop talking you can say "be quiet please" but usually in america you would follow it with a reason why, so you are not rude. such as "Hey man can you hold on for a minute i am on the phone" or "Can you please be quiet while i am watching this move?" Sometimes people talk a lot and don't realize it, so just let them know. "can i get a word in for one second" "Hey, let me say something real fast" most people in america just get louder untill the other person stops or pauses. It all depends on the situation, but a simple Shut up, is usually taken very rude, say "can you be quiet because i need to..." or "can you be quiet so i can..."

Reason + Polite Request + Thanking other person. "I'm on the phone" + "Would you mind lowering your voice just a little bit?" + "I'd really appreciate it". Hope that helps.

There is no polite way to tell someone to be quiet when you're not arguing. Best way to do it is when you get a chance to talk. Cut yourself off and then possibly looking at your watch look 'suprised' and then say "Oh, I have a previous engagement to tend to, I'm a bit late. Let's talk later" Obviously not in one whole sitting or they'll know you're itching to escape. Let me make a scenario... Trap:"So then Jill said to me that she wanted the dress but I was like oh mmm I dunno what do you think?" You:"Oh yeah I think that dress would be nice.. oh my.. the time!" Trap:"What's wrong?" You:"I have a previous engagement! (I planned to meet...) and I'm running late!" Trap:"Oh I'm sorry, didn't mean to hold you up." You:"No it's ok, I'm sorry, I didn'tplan well." Trap:"Ok, bye" You:"I'll talk to you later, and about the dress too!" It is rude to look at your wristwatch when someone is talking to you but if you casually make a pass on your watch as you're talking it should be less offensive. Along those lines? ^^ Looking at the first two comments if you mean for them to be quiet whilst you're intending to stay... I agree with them but as for old people.. it's harder. As for chpri's "Hush, please!" That's rude!

The most polite way I can think of is, "Hush, please!"

shut up(but this is not polite) could u please stop talking right now?(this is much better than the first one)