This kind of shit happens a lot. Married deputies often have their girlfriends meet them somewhere on their beat. Counting on their partners to keep silent. Or one of the groupies will be at some secluded location and you can have a couple of units circling thru the area, waiting their turn for a quick blow job.
For a time, in one of the Lost Angeles po-po stations, the duty Sgt would go out unannounced if the number of units in a certain area were a little heavy.
A unit might call out if they saw the Sgt. apporaching the area, "Hey Sarge, just saw you on MLK, do you need assistance?" Then the coppers, alerted would would take off for other areas.