“We should really go to bed so these nice people can leave.”
Charles Grodin says he was at a party once where the hostess told him “It would be so nice if you weren’t here.” Grodin liked the phrase so much he used it as the title of his memoirs.
Turn off the air conditioner.
Or, hypothetically, if you’re somewhat impaired, and you’re trying to break up an out-of-control house party, you might go down to the basement and start flipping circuit breakers in an attempt to cut the power (and thus the music) in the rooms that are full of unwelcome guests.
Of course if you’re too impaired, you might not notice when you’ve cut the right circuit, and flip it back on, and then a more lucid housemate figures out what you’re trying to do and takes the more straightforward “party’s over everyone” approach.
Slide show. Bonus if you can hire Ben Stein to narrate for you.
Herea guy fired a shot to get his guests to leave.
My friend Teresa got the whole party to chant
“Give me a G”
“Give me an E!”
“Give me a T!”
And so forth continuing through THEFUCKOUT
And then proclaiming:
“What does that spell”
…Que a bunch of drunk people thinkign real hard for a minute…
Ohhhhhhh
If it’s a high school or college party frantically screaming that the bitch next-door called the cops usually does the trick.
Tell them to get the fuck out and call the police did you really just post this? You have people in your house you do not want there.
Put a Bruckner symphony on at very high volume. Guaranteed.
When we were living in Indonesia, my dad often entertained our Chinese parishioners who just didn’t pick up on our Western social cues (looking at his watch, yawning, asking my mother if the dog had been let out before it was time for bed, etc.) for when it was time to leave.
Finally, he hit upon a brilliant strategy. When it was time for the gathering to end, he would simply wait for a lull in the conversation and say, “Well, before you go, why don’t we have a word of prayer?”. Then he would stand up, close his eyes, and start praying. He would specifically pray that everyone would have a safe trip back to their homes.
Worked like a charm!
You could also try spraying them with a water bottle - it works on cats.
I have the LP of “It’s a Small World” if anyone wants to borrow it. I’m not likely to be in a position where I’d have to use it.
Turn off the master switch at the electical box and go to bed.
I believe the OP is asking if you have a legal right to use physical violence or at least very physically aggressive methods to get rid of guests who’ve stayed past their welcome. In other words, how far can you go to get them to leave? The few places that have laws (castle laws) allowing property owners to use violence against trespassers usually require the owner to show a clear and imminent danger to their health or that of other occupants. Taking a baseball bat (or worse) to unwelcome guests that you are not in grave physical danger from would get you in all sorts of trouble. Even if they are leaving drink rings on your mahogany coffee table. 
Assuming you have no illegal substances in your home or body, I would call the police. Quietly, so that none of the guests that might happen to be in possession of said illegal substances have a chance to throw them under your couch and thus get you in trouble. If you are in possession or under the influence of any illegal substances, I would tell them that a neighbor has called the police (but not actually call the police). Or you could try what some of the others have suggested, make things so uncomfortable or annoying that everyone will leave of their own accord. Under no circumstances should you turn off the lights or other things that could lead to your guests injuring themselves and filing lawsuits against you.
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Moved to IMHO at the OP’s request (since the original question has been answered to the OP’s satisfaction and the thread has become IMHO anyway).
[/moderating]
I’ve got a spare of Pil’s “Flowers of Romance” if anyone needs it. It didn’t work for me–it just made the unwanted guests look at me funny, but maybe you’ll luck out and yours have more sensitive ears.
Really, are there any of life’s problems that the Family Circus hasn’t addressed?
So…did they ever think about, say, not inviting people over?
“Wreck of the Edmund Fitzgerald” is my house clearer of choice. On repeat if necessary.
The OP sort of implies that it’s his friends (since he invited “some people” over, not that he’s having some huge blow out party). Maybe I’m wrong, but what I take away from the OP is a lot less. . . malicious than a lot of you-- just some clueless friends who can’t catch on to the fact that he wants to go to bed. C’mon, we’ve all been in this situation.
I’m the straight forward type, so I’ll just say, “Alright, I’m exhausted. It was nice having you guys, but I’ve got to get to bed. Thank you for coming!” All while walking toward my front door (to hold it open for them, not to leave :)).
Call the police? Seriously? Oh, Straight Dope. . .never change.