There's a lovely story of a dad who's wife said, "Lil Johhny said a bad word today. Go talk to him." Or something to that effect.

"Johnny, Momma tells me you said X. That's pretty bad, but at least you didn't say the worst word..."

"What's that?" "Can't tell you!" <negotiations> "OK, but you have to PROMISE you'll never say it in front of Momma. It's <whispers> booglashek."

Next day, all his friends were over, calling each other booglasheks.

Percy Livermore: We must rid our speech of slang. Now, besides "OK", I want you all to promise me that there are two words that you will never use. One of these is "swell" and the other one is "lousy".

Lucy Ricardo: OK, what are they?

Percy Livermore: [with emphasis] One of them is "swell" and the other one is "lousy".

Fred Mertz: Well, give us the lousy one first.

I spelled around my daughter. This worked until, between 3 and 4 y/o, she asked a preschool teacher what "F-U-C-K" spelled. The teacher asked where she'd heard it and she said her father spelled it a lot.