[michaelt]

"Passing off" in this context doesn't mean something being passed to another party, like a sportsball player making a pass.

Rather, it's a common law term for selling an item while misrepresenting its origin [1] - for example, if an ebay seller claims to sell real rolexes and sends out fake rolexes, they have 'passed off' the fakes as real. This can happen even in the absence of registered trademarks.

Of course, most of the historical examples are of copycat products - but the definitions used on Wikipedia sound like it might cover misrepresenting restaurant partnerships - particularly if the restaurant's reputation is besmirched by inept deliveries.

[1] https://en.wikipedia.org/wiki/Passing_off