"One more strike and you're out of the EU", which is classic dirty tactics from the federalists.
The bullying didn't work, the branding didn't work, so they'll try threatening next time. It's also 100% false, and the point will be highlighted to ease No voters concerns.
Whatever Merkel and Sarkosy say, Cowen won't be THAT stupid to force us into another referendum unless he's certain he'll win it. That will require a massive swing in the polls, which is unlikely anytime soon.
"One more strike and Cowen's no longer PM" is a favourable counter measure. :)