Well the direction seems to be down, with people skeptical about the mess in Europe really being over, understandably worried about the impact of ridiculous gas prices affecting the consumer, and slowing improvement in the job market.  So I'm not big on picking shorts but I can see the bear case for Groupon.

"The company is coming off of a rough week after it came to light that the SEC is considering an investigation of it after the company said it would have to revise its Q4 results due to a failure to allocate an adequate reserve for customer refunds. The short interest is unlikely to dissipate until Groupon is able to instill confidence in investors regarding the reliability of its financial statements." - from a Marketwatch story

There's really nothing Wall St likes less than a company it can't trust.  And it was already not making money.  There were already many concerns about whether they had any 'moat', whether a competitor could come in and outdo them quickly... and the obvious question of whether it's some kind of fad.

I do think there is some fatigue among people for GRPN offers.  Everybody has a story of something they bought which then expired. Or they didn't realize what the fine print was.  So I will say I think this will continue to spike down.

Considering that pre-IPO GOOG offered $6B for the company, the valuation is likely to decline to that point before it turns back up (if it does).