Text says it's excluded, it's not. Code tries to exclude it in the loc_vars function, it fails. Relevant line 37 in Entropy 1.3.3.
In my opinion, probably should exclude itself in the can_use function, so that you don't accidentally waste it. Fool tarot card does it this way.
My Consume-able joker had a nice time though, looked like he was enjoying himself, so I give this bug a half-eaten cookie out of 10.