You can be paranoid and assume things, but that only saves you if your assumptions are correct. In fact, if your goal is to avoid the NSA (or the cops/FBI/whoever in your acquaintance's case), having the wrong assumptions would be detrimental in that you'd be expending a lot of effort to avoid authority with no gain in security. Never mentioning drugs over the phone doesn't help if the police never tap your phone but the guy you just sold to is an undercover cop.