That's just plain BS!

I had just finished my regular perimeter patrol of home base (one of many). With three dogs, three cats, four birds and "The Boy" inside this is a necessary part of my day.
All was well in DivaLand so I made myself another cup of joe and sat down to read the Sunday paper. Yes I know it's Wednesday but that's another story. "The Boy" was playing video games and talking to the characters..doesn't everybody?
Suddenly he yelled out.
"MAN..THAT IS JUST PLAIN BS!" What? My precious child using semi-bad language ( Well he did just use the letters).
"TOM! language mister....that's a bad word (sorta)" Of course in a typical male fashion he just nodded and continued playing. But a few minute later..
"OH.. YOU ARE JUST SO BS!"I decided to give his Dad a stern lecture on construction site talk in the home as I went to confront the guilty party.
"Sweetie, didn't Mom just ask you not to say that ?"
Glancing up from the game he looks puzzled.
"No, you said it was a bad word, not I couldn't say it" Damn it! He was right so I took another route.
"Well it means a bad word..er..words and you shouldn't say them. Do you even know what they mean?"
"Sure" he said smiling. Sure? I'm a bad Mom....
"What do they mean?" I asked getting ready for it.
"Bergin Snergin..I made it up from the letter sounds we did the other day...B and S "
Homeschooling...not for the faint of heart.