If you take the nerve of a groupoid, you get a Kan complex. Question: Take a bicategory that has adjoints for 1-morphisms, which is one notion of 'weak' groupoid (if the only 2-morphisms are identities, then such a bicategory is a groupoid), and take its nerve. Is there a name for a bisimplicial set arising in this way? Does it have some nice properties? For example, is there a model structure on $\mathbf{ssSet}$ such that these are fibrant?