If you search youtube for something like “put telemarketers on hold”, there are lots of choices. I sometimes play https://www.youtube.com/watch?v=PLzUPz2-aD4 for telemarketers. I have no idea about its effectiveness, but it amuses me. There’s typical telemarketing music, then “Please hold. A family representative will be with you shortly.” More music... “Please continue to hold. Your telemarketing b*** s*** is very important to us.” More music... “Why not get a real job? Visit www. findarealjob.com.” More music... Etc.
That’s great.