Groupon was slapped with a lawsuit accusing it of illegally using peer-to-peer advertising company by little-known Blue Calypso.
Blue Calypso said today in a statement that Groupon is infringing on two patents related to its digital word-of-mouth marketing business.
"As companies try to monetize their social media connections, they are rapidly moving into our technological area of expertise and it is imperative that we protect and secure what we have built," Blue Calypso CEO Bill Ogle said in the statement.
CNET contacted Groupon for comment, and we'll update the story when we get a response.
The frequency of patent lawsuits have exploded over the past few years -- particularly in the technology area, where companies attempt to outmaneuver each other, or extract heavy licensing fees. Apple and Samsung Electronics, for instance, are having it out in a court in San Jose for the next several weeks.
It's unique that got Groupon got hit because it doesn't sell any technology products or services, instead using technology to sell group discounts to individuals.