Sen. Cory Booker earned one of the biggest laughs of the fifth Democratic debate on Wednesday when he cracked a pot joke at Joe Biden‘s expense. “This week I hear him literally say that I don’t think we should legalize marijuana. I thought you might have been high when you said it,” Booker quipped. Although the joke lightened the debate’s mood for a moment, the exchange highlighted how far opinion on marijuana legalization has shifted over the last few years.