If you hang around gamers long enough then someone is eventually bound to exclaim "It's on like Donkey Kong!".  I've never really understood why, however.  The sentiment doesn't really seem to mean anything at first glance.  Donkey Kong has never really been on, nor does "on" rhyme with "Kong" as the speaker intends (you try rhyming "on" with "ng" and see how far you get).  Nintendo sees value in it though, as the company has announced that it has filed a trademark claim on the phrase with the aim of bringing it under the company's legal umbrella.  Nintendo says:

In honor of the upcoming Nov. 21 launch of Donkey Kong Country Returns for the Wii™ console, Nintendo has filed a request with the U.S. Patent and Trademark Office to trademark the pop-culture phrase “It’s on like Donkey Kong.” For those unfamiliar with the term, “It’s on like Donkey Kong” is an old, popular Nintendo phrase that has a number of possible interpretations depending on how it’s used. In addition to Nintendo’s use, it has been used in popular music, television and film over the years, pointing to Donkey Kong’s status as an enduring pop-culture icon and video game superstar.

The timing of this announcement amuses me because just yesterday I saw a Donkey Kong t-shirt for sale online emblazoned with this phrase and I had to wonder if Nintendo was getting a cut of the profits.  Now, it seems, they will.  Just remember to license the phrase before you try to sell a t-shirt of your own like that.  If not, then Nintendo's lawyers will be on you like... something, I guess.  While we're on the subject, here are a few suggestions for future Nintendo phrase trademarks: "Your princess is in another castle!", "Hey!  Listen!", and "[Kirby inhale noise]".