I got this idea when a member of the Human Rights Study Group of the Tokyo Sanitation Workers Union gave a presentation on Hate Speech and Racism. It is always good to stretch before running, to loosen up our conceptions and assumptions.
The Flow:
The Joker writes the words Hate Speech on the board. Check if everyone understands the concept, maybe ask for a definition.
Then write "Love Speech" on the board and ask for examples, explaining that we are looking at the opposite of Hate Speech.
You can then have people practice making love speeches, slogans, or posters.
As people suggest examples, look for patterns and grey areas.