Humans are controlling animals. They try to shape everything to their liking. The environment, themselves, and the people around them. Especially their offspring, whether they admit it or not.
 
As new dads, we are well-intended but naïve. We believe we will always manage to control what we say and how we act around our kids. We think it is possible always to give a good example.

Foolishness! Real life is messy, and kids grow like a patch of fresh dirt: one can sow grass seeds but can't prevent the wind from bringing other vegetation to take root.

What's more, kids are excellent at picking up things you don't want them to pick: our one-time bad behaviors, recurring bad habits, or occasional bad language.

There's a permanent ban on foul language in our house. We go out of our way to tell our families and friends to watch their mouths around the kids. But you can't control the wind.

The ramp from the road to our driveway is quite steep. Two weeks ago, as I was backing the car on our driveway, I got careless, and the ramp shook the vehicle.

"WHAT THE F!" my daughter exclaimed.

Not a f-bomb, but a close one. I looked in the rearview mirror to catch my wife's sight, a pinched smile of shame on my face. I know for sure she heard that one from me. Not often, but it only made it more exciting and sticky.
You can't control every little thing you say and do around them. Your kids and mine will learn things from us that we don't want them to, and that's okay!

Do your best, and regularly tell your kids about the importance of adjusting the language to the situation and the people around them.