The FBI Sends An Agent To Infiltrate The IRA

They know that he has to pass him off as Irish, otherwise they won't accept him.

So they send him first to random cities, where he learns the accent, the mannerisms. Few weeks later he starts to learn how to speak Irish.

He spends some time in the Gaeltachts (Irish speaking areas) of Galway, Mayo, Kerry. All grand, nobody suspects a thing. It's now time to travel up to Belfast to meet his IRA contact.

They meet and he speaks perfect Irish with the perfect accent.

IRA man goes, "sure, you're not Irish, are you?"

FBI guy is confused, he's spent so long working on his cover and should have been perfect. He asks, "what makes you think that?"

"Sure, aren't you as black as the ace of spades?"