Illegal to tell someone that they are speaking to undercover cops?

[HeyHomie]

Related and possibly relevant thread here:

To What Extent Can Someone 'Out' An Undercover Police Operation Without It Being A Crime?

Something I thought of while ruminating on this. Let’s say that the police are doing a prostitution sting. I recognize the bait hooker as an undercover cop, but I decide to have a little fun with her. I offer her $100 to sit quietly and listen to me talk for half an hour. No streetwalker in the country is going to turn that down, but an undercover bait hooker would miss out on half an hour’s worth of busing johns if she took the offer. But then again, she’d blow her cover if she refused. If I …