So what made Valérie Plante and Greta Thunberg laugh during their photo-op?

VALERIE PLANTE AND GRETA THUNBERG

Montreal mayor Valérie Plante has spilled some of the beans about that photo of her and teen environmentalist Greta Thunberg enjoying a good laugh last week.

Thunberg was in town for last week's massive Climate Strike March and visited city hall afterwards.

She and Plante were photographed laughing as Thunberg was signing the city's Golden Book reserved for dignitaries.

Plante told reporters yesterday it was simple as this: Thunberg had signed her name in tiny script in the huge book, prompting a suggestion by the mayor.

"So I said, 'You know, I always tell people, are you willing to draw something but everybody said no. Are you up for the challenge?' She started to laugh and she made this little drawing in the book," said Plante.

So what was the drawing?

"I'm not telling!" laughed Plante.

The Golden Book has been signed by various visiting dignitaries including actor Al Pacino and former Expos manager Felipe Alou.