When my (now) wife first began dating, she was having a torrid little affair with a co-worker half her age.
She used to call me and let me know when he was at her house bu never got to listen to anything.
However, just about a year ago, a friend of mine from home fucked a common friend, and I got to listen over the phone. He was aware before they even started, and quickly warmed to the idea, and wound up enjoying himself immensely!
From hearing their first few kisses at the beginning of foreplay, to hearing him fuck her pussy AND ass, to hearing him cum in her mouth while she sucked him off, I got to hear it all!
It was GLORIOUS!!!