illicit sexual act

The baby was undeniable proof that an illicit sexual act took place.

It had been weeks since he'd sent the medical examiner the unidentified black hairs found on the servant girl accused of an illicit sexual act with a dog.

In his charge to the jury in that case, the judge was at pains to discredit the witnesses who described their participation in illicit sexual acts.

For all I knew, the noise I'd heard was the popping of a champagne cork and Sharon was in the darkened bedroom performing illicit sexual acts with a little show dog and a whip.