What game is this d6 with a blank two for?
Considering that that looks like a very generic die it might actually not be from a game but instead from a magic trick / illusionist kit.
I'd post a link to the various online stores that offer them, but none of them had a whole lot of information about how the trick would work.
It boils down to switching it out with a regular die though.

Of course it very well might be from a board game, but custom dice tend to have some flairs or branding or even a colour.