A few years ago I bought Libby a Smartphone for her Birthday.
For a prank - I pre-loaded it with a ring tone I constructed by combining a very loud and piercing Nokia ring tone with my voice inserted as might be spoken by a Butler.
Later, we went to our local retail park and I accompanied her into Next for her to browse and buy a couple of clothes. She joined a long queue at the payment desk which snaked back and forth a couple of times - then when she was in the middle of the queue and surrounded by people I phoned her.
I was half way across the shop and could hear it clearly and was amused to see everyone looking around wondering whose phone was ringing and laughing at the strange message it was loudly broadcasting - as was Libby. It took quite a while before she realised it was her new phone. That was the day I discovered she knew how to swear
However - she still uses the same ring tone today - rather than embarrass her, it now amuses her to see people's reaction
This is it - note that on the phone it repeats and repeats until the call is answered.
http://drive.google.com/file/d/1PI6SDvjURdFzWrV_0a-gko4AqHnGtFsN/view?usp=sharing