I do it all the time.
On the radio station I listen to: betwen 5:00 and 6:00 p.m. they have this little thing they call "cruise control." The DJ asks that everyone who sees a cop hiding anywhere to call in immediately and report where they are so everybody else slows down and doesn't get pulled over. Every time a song is over, the DJ announces where all the cops are. I call in all the time. At first there was a big stink about it and cops kept calling telling the DJ to stop. But he found out it wasn't illegal and if anything, it actually encourages safe driving. Now that portion of the show is sponsored by a local DUI attorney haha. It is hilarious when a cop calls in and tries to give the DJ hell. The DJ always just says "So you don't want everyone to slow down and be safe?" And the cop is always like "Uhh.....uhhh.......uhhhh....." then usually says something stupid and hangs up.