A currency trader made a $100 million bet with a cell phone.

So says J.P. Morgan Chase & Co JPM, +0.42% Chairman and Chief Executive Jamie Dimon during an interview on Yahoo Finance Tuesday after the release of his annual shareholder letter.

While providing little in the way of detail about the specifics of the bet, Dimon joked that the $100 million trade spoke to an important market truism: people shouldn’t drink and trade at the same time.