NEW YORK -- The online world got an April Fools' Day makeover as YouTube rolled out 1911 viral videos and Google played with its fonts.

Lighthearted pranks are an annual Web tradition on April Fools' Day, with jokey redesigns and parody products.

Comedy video website Funny or Die, which last year became "Bieber or Die," turned into "Friday or Die." The site's home page was taken over by teenage viral video star Rebecca Black, complete with "Behind the Music"-style featurettes on her song "Friday." Escape was futile: Even pressing "back" in one's browser only added Black's lyrics to the address bar.

Google, always one of the most ardent April Fools' Day celebrators, launched "Gmail Motion," which allows users to mime directions to their email.

Google also played a trick on typeface fans, claiming that after extensive research, it would on Monday make Comic Sans the default font across all Google products. Search the more beloved "Helvetica" on Google, and results come in the less esteemed Comic Sans.

YouTube remade such viral videos as the Annoying Orange and the Keyboard Cat in scratchy black-and-white silent clips, purportedly from 1911. (Keyboard Cat became Flugelhorn Feline.) Hulu took a similar approach, dating their video repository to the Web's dial-up days of 1996.

Cable network Animal Planet sent out a joke press release announcing a deal for the famous escaped Bronx Zoo cobra -- news that some outlets reported earnestly. Grace Suriel, a spokeswoman for the network, said it was merely "wishful thinking" if anyone took the release seriously.

Most of the April Fools' pranks were harmless, though. The business-centric social networking hub LinkedIn offered unusual connections in its "people you may know" section, including Groucho Marx and Sherlock Holmes.

The software developer Atlassian launched its own version of the enormously popular mobile game "Angry Birds": "Angry Nerds."