I was once pulled over for not wearing a seat belt even though I clearly was. He then asked, "Are you calling me a liar?".
Cool. I say "yes" and I don't know what kind of trouble I am in. I say "no" and I get a ticket even though I am wearing a seat belt.
I just replied with "I am wearing a seat belt." and of course he wasn't happy about that either. I just don't like his initial question to which there is no correct answer.
Do you know why I pulled you over?
*Would you like to incriminate yourself?*
Not really a question, but they'll casually mention going to get fingerprints or something in hopes that you'll say "ok, fine! It was me!"
I know a guy who fooled everyone. He wrecked his car and then tried to claim his car was stolen and the thief crashed it. He made it believable. I believed him. All our friends believed him.
The cop had doubts and mentioned that he'd dust the inside of his car for prints. The guy buckled and admitted.
I later asked why. "Because he was going to get my fingerprints."
I replied "well, no shit. It's your car. Of course your fingerprints are there."
The most common technique is just to ask the same questions over and over and record the answers. Typically you don't respond the same way every time and eventually, if you're trying to hide something, cracks will appear in your story. Better just to shut up.
Police officer got me pretty good. Pulled me over at a speed trap. And after a series of questions asked if I thought I could have been speeding and I said yeah probably. And he wrote on the ticket
"Admitted to speeding"
"Do you know what the speed limit here is?"
"No officer I was driving much too fast to read those tiny signs"
"You're not from around here, are you?"
Have heard of some rural cops using this on people, making up some b.s. local ordinance they "violated" and then downplaying that into a different offense they didn't commit. Had one time where I was pulled over for making a legal right on red and had the officer pull me over and tell me he was going to mark it as a noise ordinance violation. He even explained it would save points on my license as it was a non-moving violation and I can just go pay that at the court house. Prosecuting attorney dismissed the charges when I showed up to contest them and explained what had happened.
Here's one I see from smarter cops:
(Sniff sniff) "I smell beer." (wait for a response)
It's not a question, but it definitely puts the ball in your court to "explain" why this officer smells beer.
While it's tempting to suggest that maybe the officer just burped, the correct response is to ask whether you are free to go. If not, it's time to say "My lawyer told me never to answer any questions or consent to any searches."
If they ask you to recite the alphabet backwards, the answer they're looking for is "I can't even do that sober."
I had a cop pull this devious tactic on me at a DUI checkpoint (note: I dont drink alcohol... at all).
So, he's asking the usual questions where are you coming from? (work) where are you going? (home) How long have you worked there? etc etc..and then he suddenly gets all casual and says "well if you ARE drunk, you sure fooled me.". I thought it was an odd thing to say and I know to be careful what I say to a cop (because of the tricks they use) so just to be safe I didnt say anything. Just looked at him. He looks away for a second, says something else (I dont remember what exactly) and then goes right back and says the exact same line. "Well, if you are drunk you sure fooled me". At that I KNEW something odd was going on. So I ask him if we were done and could I leave? At that he let me go.
Later, after trying to figure out what that was all about I realized if I had said anything to the affirmative (yes, uh-huh, or even nodded) it would be as if I said "yes, I AM fooling you... I AM drunk".
IMO a pretty despicable way to get someone to unknowingly admit guilt to something they may not even be guilty of.
Officer: "Do you know how fast you were going?"
Man: "I was just keeping up with traffic sir"
Officer: "Traffic?! There isn't another car on this road for miles"
Man: "I know. Thats how far behind I am"
Do you know what speed you were going?
No officer, of course I don't, I had no clue I was 25 over