One of two things will happen when you socialize with others. You either become like your companions, or you bring them over to your own ways.
Most of us do not possess sufficiently developed steadfastness to steer our companions to our own purpose, so we end up being carried along by the crowd. Our own values and ideals become fuzzy and tainted; our resolve is destabilized.
It's hard to resist when friends or associates start speaking brashly. Caught off guard when our associates broach ignoble subjects, we are swept along by the social momentum. It is the nature of conversation that its multiple meanings, innuendoes, and personal motivations move along at such a fast clip they can instantly shift in unwholesome directions, sullying everyone involved.
Until wise sentiments are fixed into you as if they were instinct and you have thus acquired some power of self defense, choose your associations with care and monitor the thrust of the conversations in which you find yourself.
~ Epictetus, The Art of Living