Do they neutrons bother the electrons or do the electrons do it to the neutrons?

whats so funny about that question?? i heard it in some old movie, and everyone started laughing. some guy was playing th cello and he kept on playing even when everyone else stopped and the conductor sneaked up behind him, and when the guy stopped, the conductor asked him, "now professor, do they neutrons bother the electrons or do the electrons do it to the neutrons?". and everyone else in the orchestra started cracking up. but i didn't get it.