Generally though, it doesn't work if you ask for a specific shot (at least in my experience). Just ask if they have a magic shot.
If they ask you to "Act cold" for instance, you'll know that it'll be an Olaf shot so if you've already done that, then you can ask them if they have another. I also sometimes ask if they have any of the less common magic shots (sometimes what they think is "less common" isn't really).
Advice used to be that photographers with a tripod don't have magic shots, however, the last few trips I have found that NOT to be the case. People with tripods do animated magic shots (not all of them, but some of them) And if they do (again, in my experience) they automatically do the magic shot first and then just regular ones (so when you ask them if they have any magic shots, they'll say they already took it).