Hanky-panky
/ˈhæn.kiː.ˌpæn.kiː/
noun
Mischievous behaviour, dishonest or shady activity.
“I think there was some hanky-panky with the last election.”
Amorous behaviour, smooching, making out, necking, sexual intercourse or other sexual activity, especially if illicit.
A debaucherous act; a sexual act that is considered inappropriate.