My youngest daughter used to never cuss. Just a total sweetheart like that. The worst thing I think I heard her say was "she act's like such a B-word!" Then she started scoring races at a local dirt track, and after putting up with all the BS from the drivers (and especially their wives) she's now out there tossing around fucks and shits and bitches and assholes and various physical threats like they're confetti...
Yes, the hard knocks of life will toughen up even the sweetest little cutie pies. And hey how did a sweetie pie get involved with dirt track racing in the first place? Surely that environment would have an influence on creating a potty mouth.
She married her HS sweetheart who's been driving since he was 14. His parents took over ownership of one of our area's tracks several years ago (there are 4 within a fifty mile radius of us) and my daughter's been scoring the races for them ever since. I did it with her for a couple of seasons back when she first started. Fun stuff...