Don't know if this has any relevance here, but there is a phenomenon called 'spit' which is becoming more common on VOIP routed calls - see http://en.wikipedia.org/wiki/VoIP_spam (hope this link is OK, otherwise search VOIP SPIT and check the wikipedia entry).
Ive experienced it a few times as swear words being randomly interjected, but I understand that prerecorded conversations or activities are alos being added now. It is possible that this is what you experienced.
I hope everything works out.
