Heckle training

I frequently run an open mic in Eastern Europe (everyone performs in English).

The comedians are great, most of which have done it for years. The "problem" is that the audience is very quiet and not engaging, and we rarely get heckled. This is a problem as we are less trained for when we travel abroad to do stand up, or when we accidentally get tourists in who heckle more.

My idea is to hold a themed open mic that encourages heckling. Make is clear for the audience that we want this training, but if you heckle you will also get put down by us.

We have done themed mics in the past, particularly around dark jokes. That worked great.

Have anyone done anything like this before? Any tips or ideas for how to put on this show?