Magic tricks, for example.
Apparently they’re called Forcing Dice; obviously they sell different ones but the concept is the same.
Obviously these dice will not stand close scrutiny so they are most effective when used sparingly, substituted for a regular die at a critical moment.
Very useful to magicians who need to force a specific number as part of a trick, or as part of a humorous routine.
I saw them with The Faint in 2008!
Relatedly, I saw The Faint again in 2009, with Ladytron.
Genghis Tron totally blew me away with their sound live, they were the highlight of the night for me.