context-specific greetings

In Bavaria and Austria, it is customary to greet people with "Mahlzeit", as long as it is lunchtime (or shortly before). It can be used as a way to welcome you into a restaurant, but more often it is used between acquaintances.

In Vancouver, it is customary to greet people with "woooooooo!", as long as it is after Canada wins hockey gold. This context-specific greeting is usually coupled with a high-five, and is to be used on every person passing you on the street.

non-differentiable likelihood functions

Are likelihood functions ever non-differentiable?

Of course, you can always transform the parameters in such a way that you get a kink in the function... My question is whether this ever occurs naturally.

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UPDATE: clearly, if the likelihood for each data point is differentiable, then so is the likelihood for the whole data.