Gerry Adams is not exactly famous for his sense of humour. During the Good Friday Agreement talks, he once told a member of Tony Blair's staff: "The thing I like about you, is that you blush every time you lie."
A British official immediately shot back: "Unlike you, Gerry," - and received nothing but an icy stare in reply.
Today, Adams has even less to laugh about. The Sinn Fein sex abuse scandal is gathering pace, exposing both his disgraceful treatment of rape victim Mairia Cahill and his notoriously dodgy relationship with the truth.
Now Enda Kenny (left) is moving in for the political kill - because the Taoiseach rightly senses that not even Adams (left) may be able to wriggle his way out of this mess.
After his own meeting with Mairia yesterday, Kenny went into the Dail and dropped some intriguing hints about what might happen next. He referred to other victims of IRA abuse who may be on the verge of coming forward.
He also cited cases of Provo paedophiles who were quietly spirited across the border by their comrades - in much the same way that the Catholic Church tried to sweep its own child rape problem under the carpet.
If these extra scandals are finally brought to light, then Adams could be facing the biggest crisis of his 31-year leadership. He can just about handle Mairia Cahill's allegations by issuing blanket denials, no matter how unconvincing they might be.
A small army of other abuse victims would force him to answer two critical questions - how much did he know about the IRA's brand of rough justice and what (if anything) did he do to stop it?
During a fantastically tense Dail session yesterday, Adams was reduced to whining that Sinn Fein's enemies are trying to make political capital out of his embarrassment.
This makes him sound like a bad goalkeeper who cries foul when the opposition keep sticking balls in the back of his net.
Of course Mairia Cahill's ordeal is a legitimate political issue - and Enda Kenny would not be doing his job if he failed to point out the many holes in Sinn Fein's leaky defence.
As the Taoiseach has tellingly pointed out, any Fine Gael leader embroiled in this kind of controversy could not expect to last five minutes. The same goes for Fianna Fail and Labour.
All these parties have their faults, but they still live in a different moral universe to Sinn Fein - and are fully entitled to point this out every chance they get.
To quote Gerry Adams's famous warning about the IRA, Mairia Cahill is not going away, you know. A full-scale Dail debate about her case will take place soon, while the Oireachtas Justice Committee plans to investigate the outrage of IRA kangaroo courts.
In Northern Ireland, the Director of Public Prosecutions has announced an independent review of three cases linked to the repeated abuse of Mairia in 1997.
While Adams braces himself for all these developments, he is faced with one basic problem.
No matter how nicely the Sinn Fein leader tries to dress it up, his version of events implies that Mairia Cahill has told lies about him.
So who are the Irish people going to believe - an articulate rape victim or the man who swears blind he was never even a member of the IRA?
In a way, it would be incredible if this was the issue that finally brought about Adams's downfall. Sex abuse is obviously a horrific offence, but it still falls short of the ultimate crime - murder.
Sinn Fein's private army committed around 1,800 of those during the Troubles and have yet to pay any major political price.
This time, however, it may be different.
Unlike most IRA victims, Mairia Cahill has lived to tell the tale. After 17 years of suffering, this remarkably brave woman is ready to break her silence - and every one of her media appearances makes Adams look desperately shifty by comparison.
Enda Kenny is starting to look like a werewolf hunter who has just found a silver bullet.
If he gets the chance, the Taoiseach must not hesitate to finish his target off.