class coercion?

I'm not sure if this is a. possible or b. what I want to do, but I'm curious: is it possible to force a Ruby class to become a different class? I'm getting this error in my rails app:

ActiveRecord::AssociationTypeMismatch (TagLocality expected, got #<Class:0x983f5a0>):

I'm wondering if there's some way to take that Class object and "magick" it into a TagLocality object, thereby solving my problems and creating world peace.

Any ideas or tips are welcome and very appreciated.

Thanks! -Jason