あり (ari; "to exist") can be used casually to call something acceptable. It's also one of the prominent lyrics of the Onimai OP, though in that case it refers to having "something" in particular, which is how it's often used in other TSF media.
Nope
なし (nashi; "to not exist"), much like its counterpart あり (ari), can be used casually to call something not acceptable. It also is used prominently in the Onimai OP's lyrics, though in that case it refers to "something" in particular going missing, which is also how it's often used in other TSF media.
