Greek. Verb. "To render unfamiliar, ie, 'it's all Greek to me.'"
In the advertising world, a 'greeked' product is one whose labeling looks familiar but, upon closer inspection, isn't actually a representation of the product you thought it was. For instance: if you see a blue soda can on a dining room table that looks to be embossed with the Pepsi logo but, upon closer inspection, has had the word 'Pepsi' in the logo replaced with the word 'Cola' or some such, that product is said to have been greeked. The word almost always appears in the past tense unless you're actually doing the product manipulation itself which is, frankly, a miniscule percentage of the population.
There are a variety of reasons to do this to a product, none of them wholesome. Generally it's because television or movie producers want a product to appear familiar to an audience but don't want to go through the legal hassle of using the real product itself, so they alter it in some way to avoid the trademark dispute.
Greeking can also be used when the use of said product could be construed as defamatory (ie, a man bludgeons an unsuspecting victim to death with a can of Pepsi. It could happen.) It's not illegal or anything, but it can cause problems later on and it's best to keep the lines of communication between the producers and advertisers open and clear without having to worry about potential negotiation roadblocks.
The greeking of products is less common nowadays that it has been in the past because product placement has become more and more common in all forms of media - it's better for all parties concerned to just knuckle down and hammer out an agreement instead of resorting to silly visual tricks. Nevertheless, the occasional obfuscated product logo still makes appearances here and there if you pay attention.