Grexit being Greek exit from the Euro, of course. Willem Buiter and Ebrahim Rahbari at Citi who previously rated the possibility at 25% - 30% (read 55% - 60%) now rate it 50% (read 80%) likely. What's more, they reckon it's manageable; the ECB would rally round to prop the Euro up, the impact on EU exports to Greece would be marginal (they're not buying much from the rest of us anyway) and our national banks have had a year to get rid of all Greek liabilities so can take the hit.
The suggestion is that Germany has made the austerity conditions just painful enough to force Greece to leave; with Greek Parliamentary elections due in April, the political class there are looking to position themselves on a platform that will win popular votes, and defiance of Germany is popular. Merkel can then, like Pilate, wash her hands in innocence saying "we did all we could to keep them in".
The Greek police have also declared their lot on the side of the strikers; the powerful police union released a statement saying its members refused to "stand against our parents, our brothers, our children or any citizen who protests". If they disappear from the streets, the government will have no choice but to deploy the army - with all the painful historical baggage that comes with it. No-one wants the colonels back.
