dump horse

A responsibility which really should be somebody else's, but which has been "offered" to you as an "opportunity" in a way that you can't refuse, effectively dumping their responsibility on you but pretending that it's for your benefit. The difference between a standard dump and a dump horse, however, is that -- despite the total lack of altruism on the part of the dumper -- the dump horse actually does benefit you, and you truly can turn it into an opportunity.