Former Mexican President Vicente Fox is using a t-shirt to tease President Trump about his proposed wall along the U.S.-Mexico border, and he’s laughing all the way to the bank.

Fox promoted a shirt depicting Trump as a baby using toy blocks to build a wall while wearing a soiled diaper made out of an American flag to raise money for his nonprofit group Centro Fox, which aims to train leaders who serve the Mexican and Latin American communities.

Thank you for all your support! @centrofox was built on the foundation of empowering leaders to take charge and give back to their communities. Help me continue to spread the message of compassion for others, by getting this apparel at https://t.co/lRhyRIWF1m pic.twitter.com/3lVcGyTLjx — Vicente Fox Quesada (@VicenteFoxQue) April 6, 2018

The shirt mocks Trump’s plan to build a wall along the southern border of the U.S. and pokes fun at the size of his hands—which became the butt of jokes during the 2016 presidential election.

This week, Trump issued a proclamation allowing the National Guard to be deployed to the U.S.-Mexico border.

Fox—the one time opposition leader of the right-wing party in Mexico—is one of Trump’s most vocal foreign critics, and has a history of ridiculing the U.S. president. In one instance, he gave Trump a giant middle finger in a photo posted on social media, in May 2016, before he apologized in a statement to Breitbart News.

Fox also regularly criticizes Trump for his tough stance on immigration. In September 2017, Fox wrote a tweet directed at Trump telling him that he cannot stop immigrants from becoming the majority in America.