Late last year, Sony Computer Entertainment America managed to annoy a massive number of internet users by trying to trademark the phrase 'Let's Play.' The term is used for commentated gameplay videos and has been around since 2007 when it first appeared on the Something Awful forums.
If Sony had been successful in its bid to trademark Lets Play, no one would have been able to use the term without first getting the company's permission. Surprisingly, the US Patents and Trademarks Office didn't originally deny Sony's application because of the phrase being such a widespread term; they rejected the PS4-makers attempts because Lets Play is very similar to a trademark held by another company.
In 2013, a Georgia-based firm that connects gamers to events registered the name LP Let'z Play of America. The USPTO ruled that as both terms are related to video games, there would likely be confusion with the mark. The Office refused the application and sent Sony a non-final action on December 29, 2015.
Now, as a result of a Letter of Protest to the USPTO by The McArthur Law Firm on behalf of the gaming community, the trademark office has updated its ruling. The update states that 'Let's Play' is such a widespread and generic term that it is classed as a descriptor, not a brand, and, therefore, can't be trademarked.
To support its rejection of Sony's application, the USPTO's evidence consisted entirely of the first two sources included in the McArthur firm's Letter of Protest: the Wikipedia page for Let's Play and the /r/letsplay subreddit.
Sony still has six months to challenge the ruling, although it's pretty unlikely that it'll attempt to, especially in light of this updated rejection. Maybe the Japanese company will try to trademark another term, such as 'game.'