Surprising The Cows

Little Johnny goes to spend a weekend with his uncle, a wealthy farm owner. 
One evening, as Uncle Ralph and his wife are entertaining guests with cocktails, 
they are interrupted by an out-of-breath Johnny who shouts out, "Uncle Ralph! Come
Quick! The bull is fucking the cow!" 

Uncle Ralph, highly embarrassed, takes young Johnny aside, and explains that a certain
amount of decorum is required. "You should have said, 'The bull is surprising the cow',
not that filth you picked up on the playground,". 

A few days later, Johnny comes in again as his aunt and uncle are entertaining. "Uncle 
Ralph! The bull is surprising the cows!" 

The adults share a knowing grin. Uncle Ralph responds by saying, "Thank you Johnny, but 
surely you meant to say the cow, not cows.  A bull cannot 'surprise' more than one cow 
at a time, you know..." 

"Oh yes, he can!" replies Johnny, "He's fucking the horse!"