"Longer Soft" joke

Sam and Abe, now in their eighties, first met in grade school. Their relationship now is playing cards, playing jokes and making bets.

One day Sam calls Abe and says "I bet you that mine is longer soft than yours is hard. A thousand dollars."

Abe replies "How can that be? If you know anything about biology you....

Sam interrupts "I called for a bet, not a lecture. Mine is longer soft than yours is hard... A thousand dollars... YES OR NO?"

Abe says, "OK OK I'll take that bet. How long is yours soft?"

Sam answers "Eleven years"