Fireman Fred is not a swear word

Sara-Jane and Jeremy have been dropped off at 6.15 each morning (aagh) for the last three days, I drop Jeremy at daycare and Sara-Jane comes to work with me, she's helping with some paper sorting.
This morning Jeremy and I were discussing music, he likes the Parlotones and Panic at the Disco, not too shabby. He started singing a song but stopped and said "but I can't say that word Granny". Too true. He then told me about swear words and pointed out that the worst one is "the F word" but, he doesn't know what it is.
"Perhaps it's Fishcakes" I suggested. "No". "or perhaps Philadelphia?" "No"
He was clearly pondering all the f words he knows when he pointed out that Fireman Fred isn't a swear word. Thank goodness. For those who don't yet have preschoolers there is this wierd way of learning the alphabet which takes perfectly simple letters (as in a-z) and complicates things by giving each one a title as in Annie Apple, Bouncy Ben, Clever Cat etc.
It makes an adult want to say sugar or even funky.