Nickname
The official firm nickname, approved in 1973, is MoFo, which is also commonly used as an abbreviation/euphemism for motherfucker. As of February 28, 2005, however, the firm has returned to the more conservative Morrison & Foerster, although MoFo is still used as the firm's url: mofo.com.
During the dot-com era of the 1990s, when it was fashionable for American companies to appear irreverent, the nickname was prominently featured in the firm's advertising, both online and offline. It gained further notoriety through a bit by Jay Leno on The Tonight Show [1]. Leno joked that the firm's clients could shout, "Get me my MoFo lawyer!"
Additionally, the popular home game Trivial Pursuit has a question and answer circulating in current versions asking which international law firm is commonly known by the four-letter phrase "MoFo". The answer, of course, is Morrison & Foerster.