Yussel and Moishe

Two older Jewish men are sitting on a park bench talking. 

Yussel says, "So nu Moishe - how is your sex life these days?" 

Moishe says, "Mine sex life is excellent, so who can complain?" 

Then Yussel says, "Oy, mine sex life isn't so good anymore. So maybe you can share mit me your secret for the good sex?" 

"Vell," answers Moishe, "I eat rye bread every day. Dus is mine secret. If you just eat Jewish rye bread, your sex life will improve!" 

Yussel decides to follow this advice and finds a Jewish bakery nearby. He goes inside and says to the clerk, "Give me all the loaves of Jewish rye bread you got!" 

The clerk says, "Do you want whole loaves or do you want us to slice them?" 

Yussel looks puzzled and says, "What's the difference?" 

The clerk says, "Well when it's sliced, it gets hard faster." 

To which Yussel says, "Nu? So how come everyone knew about this but me?"