It seems Yankel was pushing 25 and he'd never been out on a date. His Rosh Yeshiva calls him into the office one day and says, "Yankel! 18 to the Chuppah! What's going to be already?"
Yankel blushes and explains to his Rebbe that he grew up in a house full of brothers, and he's never even spoken to a girl anywhere near his age. He doesn't know what to say to girls. Besides, it would interrupt his learning.
The Rosh Yeshiva puts a fatherly arm around him and tells him "Don't worry about your learning, this is a Chiyuv with a capital ches. And as for what to say, you can talk about her family, you can talk about what she likes, and if all else fails you can talk philosophy."
Yankel leaves the Rosh Yeshiva repeating under his breath, "Family, likes, philosophy. Family, likes, philosophy. Family, likes, philosophy." Finally, the day arrives and he goes out on his first shidduch.
The young people sit down in the hotel lobby and look at one another uncomfortably. Yankel realizes that he's going to have to say something, and the first thing on the Rosh Yeshiva's list is family, so he blurts out, "Do you have any brothers?"
"No." replies the girl, and silence reigns.
Yankel thinks hard, and then comes up with, "Do you like baseball?"
"No." is the immediate reply.
Now Yankel is really at a loss. Ah yes! Philosophy! So Yankel leans forward, and very intently, in his best talmudic tones, asks "If you had a brother, would he like baseball?"