I love the Geico commercials that were on the radio stating, "We all do dumb things sometimes, but paying too much for car insurance doesn't have to be one of them." It's true that we all do dumb things, but I would suggest that hurting your testimony and Jesus' reputation doesn't have to be one of them.
I was out with some business people yesterday, two of which are Christians and one who is lost. The two Christians were both smoking, I heard one of them swear on a few occasions, and the other suggested that we all go get some booze. What must the lost person's opinion of Jesus been after seeing the behavior of these Christians who supposedly have been saved out of sin? My experience is that lost people know that Christians shouldn't drink, smoke, or cuss and that the Bible commands them to be Holy, so this behavior reinforces the view that Christians are "hypocrites". Hey, we all do dumb things sometimes, but hurting your testimony in front of those who need Christ doesn't have to be one of them.
 But as he which hath called you is holy, so be ye holy in all manner of conversation;
 Because it is written, Be ye holy; for I am holy.