Adding on to this question, do you anticipate the same people capable of tapping phones to think less of you for a dirty joke? The people whose opinion of me would lower for something off-color and the people who possess the ability to wiretap me are a disjoint set lol.
The point is it would be usable against you, but at the point you are wiretapped and can be used in court all bets are off you are probably in too much trouble may as well tell the joke!