Double-take

I was leafing through the only book in the waiting room, a book about the origins of words and phrases. Being a dyed-in-the-wool spanko, I flipped to the chapter on S words, and scanned it quickly.

Aha! I quickly hit pay dirt; an interesting-looking entry:

Spanking. What is the reason love-making is called "spanking"?
It's because kissing can produce a tingle that's not unlike that produced by a static electric "spark".

Spark? What does that have to do with.... I reread the entry again and realized my mistake. It was "sparking", not "spanking". Honestly, I guess the light must've been dim or I was tired and my eyes were playing tricks on me. I swear I saw "spanking".

There was an entry for "whipping boy" too, but I hesitate to mention it here in case it was actually "whiffle tree". I had to drop the book when the receptionist called me in for my eye examination.