For openers, I think people can get thrown off when they're waiting for a response they previously envisioned. When the girl doesn't a certain way, they get totally thrown off and start panicking. When people have an opener in mind, they should also have lots of prepared reactions.

These may not work but just an example of how I think openers should be prepared before using

Opener: How much does a polar bear weigh?

girl: ummm i don't know
guy: enough to break the ice!

girl: i've heard this one...enough to break the ice
guy: nope 1355lbs...how much does an orca weigh
girl: no clue(or some random number or something else)
guy: Enough to break the ice!

girl: some bitchy response, blows you off, etc.
guy: I guess not enough to break the ice. How about an orca?
girl: haha positive response whatever, it worked hooray!!!
or
girl: you're not funny, something mean (o noes!)
guy:not even an orca. good god you are icy!

Have you been successful in using this polar bear opener?

I've used the original and it got a few giggles but then I just ejected cause I didn't know what to say after. I then tried again a while later with some other girl and was more prepared. After she giggled I said, "ahhh it worked I guess you're friendly" and talked to her for a little. I've never tried that orca line but it just made me realize how important planning post-opener is. Planning for negative, positive, playing along, etc. is really helpful.

My mates and I tried that line once.
My mate got blown out straight, they just walked away.
When i tried on a 2 set, it worked they started talking for a while but i couldn't manage to transition, so i ejected myself.
It really doesn't matter what you say, its how you say it. Lots of eye contact, no fidgeting, proper posture, and practically anything could work.

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Welcome to my reality ~ DeAngelo

Yea that line is pretty awful. I should have probably used a different example. I typically avoid canned openers.