If the experimenter knows what distribution you expect, they may decide not to use that distribution. And unless you're the first person in the experiment, they have in fact been learning what distributions people expect, though not you in particular.

What you could do is run your own similar experiment on regular subjects first so you know what the experimenter is likely to expect, and then impersonate a regular subject when you are called into the experiment, up until the point you get offered a bet. I don't think they would have accounted for that possibility, and even if they did it would be rare enough to still be unexpected.

But make sure the financial incentives to do this aren't enough that other people do the same thing or it will ruin your plan. You have to be satisfied with outwitting the experimenter.