Spoilers-
ROTN-’ My friends and I have been using a hidden camera to take nude footage of you and your friends. Earlier today, we printed nude photos of you and sold them. I just tricked you into having sex with me. How do you feel about all this?’
‘I love you!!!’
RG
‘This hot chick all the guys are chasing wanted to have sex with me. But I’d rather have sex and a relationship with you’
‘With me?’
‘umm can we?’
‘YES!!!’
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That bit of dialog isn’t with Jordan.
Yes, I know, though I see how my post might have suggested that I thought it was.
I thought the science in the movie (the isolation table, lenses, and so forth) was more realistic than most movies. And this gag (Mitch first attends full class, then we see a few students have just left tape decks to record the lecture, then more tape decks and finally at the end, the classroom is full of tape decks and the lecture is being played on a reel-to-reel deck at the front) was pretty funny.
The devices evaluating coins in the old coin-operated vending machines used to make sure the coins were the right weight (to reject slugs, subway tokens, foreign coins, etc.). They also had magnets to reject those magnetic Canadian nickels. If conductivity were the issue, slugs and Canadian coins would have worked just fine. But frozen water would have been way to light to be accepted by the mechanism.
UI don’t recall the dialogue associated with the scene, but if they said the pass/fail mechanism was based on conductivity, then they were lying so they could have the scene play out the way it did.
Another thing that bothered me was that the damned frozen coin would probably have gotten itself stuck in the slot, at least for a time. And it’d have to melt somewhat in order to conduct electricity – completely solid salty water ice isn’t going to conduct anything.
Maybe it was heavy water. 
Heavy, man!
Magnets can also reject coins of the wrong conductivity. A coin (even of non-ferrous metal) rolling past a couple of strong magnets will develop eddy currents, which will have the effect of slowing the coin down. How much it’s slowed down will depend on the conductivity of the metal. And once you have different coins rolling at different speeds, it’s easy to roll them off the end of a ramp into different bins for the right coin and the wrong coins.
But to be completely fair, that frozen substance was a Macguffin of the movie, and they never actually say what it’s composed of (it’s not just frozen water or carbon dioxide), so we can’t say what its physical properties were, and it’s conceivable that it did have the right properties to fool a vending machine. It’s also possible that the vending machine had previously been tampered with by other nerds, so as to disable some of the counterfeit-detecting mechanisms.
Some vending machines are more sophisticated than others. The washers and dryers in my dorm in college just needed something that would physically trip a switch when the coin slot was pushed in, and for the slot to be pushed in all of the way. Yes, it could be easily defeated by a wire, a slug, gluing a string to the coins so they wouldn’t fall, or even pulling the coin slot back out very quickly so the coins never fell.
Laszlo was also married to Tanya in The White Lotus. He looked really different.
I seriously doubt it.
i think they just used it because of the Rule of Cool.
Kilmer using Middle Eastern dinars to fox the machine wouldn’t be high tech or cool enough.
McKnight: “Sure, go ahead. Take all the time you need.”
McKnight: “WHAT IS TAKING SO LONG?!”
I use that line out loud all the time to refute people who do this in daily life to others with no irony whatsoever.
This line from Chris was also pretty good, “Jerry, if you think that by threatening me you can get me to be your slave… Well, that’s where you’re right. But - and I am only saying this because I care - there are a lot of decaffeinated brands on the market today that are just as tasty as the real thing.”
And I thought I read an oral history of the making of the movie, but can’t find that now. One page did, however, point out that this film was released only a month after Back to the Future. So it might have been overshadowed a bit.
Mitch asks if it’s liquid nitrogen when Chris pulls out the thermos. It’s obviously not liquid nitrogen, but I think the script intended the audience to understand that it’s a column of frozen nitrogen. Which probably presents its own problems - I doubt you can keep nitrogen solid in a kitchen freezer, even with a fancy science thermos. But I don’t think it’s meant to be some super-science material, just something that would be pretty standard in an advanced lab setting. Otherwise the big break through in the movie isn’t really laser tech, but materials tech, and that’s in a different building.
But also, there’s basically zero chance that a vending machine in that dorm wouldn’t end up heavily modded. I wouldn’t be surprised if you could set it on it’s back and drive it around the campus like a golf cart.
Here is a webpage from IBM describing how in the early 1980s, a comp sci grad student at Carnegie-Mellon built a system to monitor externally the status of a Coca-Cola vending machine so he didn’t waste time walking down to it if it was already emptied.
So, yes, I could believe that kids at a tech school might hack a vending machine. (Though too much of that and the company that owns the machines will just remove them.)
“You’ll have to answer to the Coca-Cola company!”
The vending machine guy probably carries a fake coin or two to make sure the machine hasn’t been compromised. Try the fake coin, and if it’s rejected, the machine is still fine. So you find out what kind of fake coin he’s using, and leave just enough anti-counterfeit measures in the machine to detect that coin, and disable all the rest.
When I was in university, my class took over the student council for our college, since no one else wanted the job. We figured out we could buy our own vending machine, and charge what we wanted for drinks. We also realized that the coke cans and beer cans were the same size…
I like to think the administration just cuts a check to the vending machine company every month for the missing sodas, and pretends like it doesn’t know what the students are doing because them thinking up ways to defeat the anti-counterfeiting measures in the vending machines is a cheap and easy way to keep them from getting into more annoying shenanigans.