Perhaps the most exciting/arousing words in the English language.There have been so many it is really hard to choose but I think my favourite two are:
Her coming to the spare bedroom after she had spent a night with her long term fwb and saying to me "I let him cum in me"
The other was receiving a text from her when I was at work and she was out shopping saying that she had called in to see another long term fwb. They had then gone into a store room where she sucked him off swallowing his load then she continued with the shopping.