So two Boro Park guys have been learning bechavrusa for over a decade, when one of them finally makes a confession.
“I’m a goy,” he says, “I got interested in your religion about ten years back and I figured the only way to really find out about Judaism is to live in your midst. So I’ve been passing myself off as one of you, and now I want to be magayer.”
His chavrusa is shocked. “My friend, we’ve been learning together all this time,” he says. “You know as much Torah by now as I do. Surely you remember learning Goy SheShovas Chayav Misah? A goy who keeps Shabbos earns the death penalty.”
“Of course I know that,” the goy responds. “So every Shabbos afternoon when I came here to learn with you I would bring my house keys with me as I walked through the streets.”
“But… but… that doesn’t help! There is an eruv here in Boro Park! So you are still Chayav Misah!”
“Not to worry, friend. I hold like Rav Belsky.”