But did Sean Penn ever imagine that he was going to be asked to be a global ambassador for the legalization of the coca leaf?
According to officials from Bolivia, this is the new task that was requested of Sean Penn on Tuesday, during a meeting with President Evo Morales.
The two-time Oscar winner was also asked if he would back Bolivia's efforts to regain coastal territories lost to Chile in the 19th century, and if he would help to convince the U.S. government to extradite a former Bolivian president.
"President Evo has asked this gentleman with his utmost respect, if he can present our claims….in different scenarios abroad, so that we can see some advances at the international level" Government Minister Juan Ramon Quintana told journalists in La Paz, Bolivia's capital city.
There's no word yet from Penn on whether he will accept this challenge. And no indication on what he could do to help the mountainous nation -- one of South America's poorest -- to regain lost territories, or put corrupt politicians on trial.
But legalizing the coca leaf could be a particularly challenging task. The plant grows in abundance in Bolivia and other Andean countries and has been traditionally chewed by indigenous groups, who draw energy from its nutrients.
But the coca leaf is also the base material for cocaine and international treaties strictly limit its sale and production.
Morales, a former coca farmer, is an outspoken opponent of U.S. drug policies.
On Tuesday he played soccer with Penn, who has become known in recent years for his support of leftist leaders in Latin America.
Penn was in Bolivia to discuss aid programs for Haiti, where he runs reconstruction programs. He might've got more than he bargained for.