- my eldest son at 2 years old... he switched letters in some of his words as most toddlers do, he also switched between French and English, 'cause he didn't know yet that he was working with two languages... "fuck" is just a distortion of the word "truck", not that he ever heard the word "fuck" around him... other words he distorted also came out sounding exactly like swear words... in French, he'd say "crisser" (québécois swear) instead of "glisser" for sliding... 

« Un » = "a"

When the boy was a small child

He was fascinated by machinery

And every time he'd see a big vehicle

He'd excitedly cry out:  "Un big truck!"

The only problem is that when he

Said it, it came out as "Un big Fuck".

Then you'd hear his blushing mom say

"Yes, a big Truck.  It's a very big Truck".