This is why I prefer "gratis" vs "libre" instead of "free as in speech" vs "free as in beer". gratis/libre are clear and succinct.
As for an actual answer: parties, weddings.
Weddings tend to have a free speech or two, too!
That only works if your audience knows what libre and gratis mean.
I'm sure this has already been answered somewhere in slashdot hundreds of years ago, but why not just go with "free as in freedom"? And perhaps use the word freedom insted of free when possible