The woman in question, a cute blonde as it happens, was pulled over for speeding by a California Highway Patrol motorcycle officer. When he walked up to her window and opened his ticket book she said:

"I bet you're going to sell me a ticket to the Highway Patrolmen's Ball."
He replied, "No, highway patrolmen don't have balls."

There followed a moment of silence while she smiled and he realized what he'd said. He then closed his book, got back on his motorcycle and left.

She was laughing too hard to start her car for several minutes.