Which one do you call?
(As it turns out, you're far more likely to call the one at the end of the suspension bridge. Here's the original study on it.)
Arousal is arousal. Scary movie dates? Not bad. How about jumping out of a plane? Gets some high marks, yep. Romantic behavior can be largely (not entirely, but largely) summed up as: Personal attention, symbols of attraction, and activity that is arousing - physically, nervously, in whatever way. You're under the influence, high on recent experience, and that high can be transferred.
This is all about an error. See, the nervous symptoms of deep emotion are very similar to those of general excitement. So if you get someone excited and present them with a potential emotional source, they're likely to just latch right on, "writing it in"as the cause, possibly even rationalizing the behavior. It's not so much an error when it comes to sex, we think - that's excitement that should cause this kind of bonding. But the kind of excitement that's being served up doesn't matter as much as you'd think.
So, if you take your date on the carnival rides, are you tricking them into maybe liking you more with that rush? Could be. But, then, you're also tricking yourself into liking them more. To some degree, we know this. We want to have a good date, a memorable thing with a nice glow after the fact, in memory. We want to get under the influence.
If you know that falling for this one would be a mistake, go for coffee.
If it'd be the best choice you ever made, do something crazy together.