This is because whenever someone calls me, I assume it's someone else's phone that's ringing because I don't usually recieve a lot of calls. But if I had a unique ringtone that nobody else had, I'd know it when someone was calling me.
A few months ago, I made my own ringtone out of Sail by AWOLNATION. But I got bored of it after a while (because I listened to that song on repeat for like 2 weeks), so I switched it to Old Telephone which is just the regular ringing. But last week, my brother was coming to pick me up from a friend's house and called me repeatedly and I didn't pick up until after multiple calls because I assumed someone else's phone was ringing.
So today, I was bored and a random thought popped into my head: the Buffy the Vampire Slayer theme song would be PERFECT for a ringtone! So I made that into a ringtone, and that's my current one. I had nothing else to do, so I made a few more (Boom Clap and Oh No, plus one for my friend).
Honestly though, I probably won't even use the ringtone all that much because nobody calls me anymore.
However, I'm sure it will come in handy at some point.
Here's how I made my ringtones: http://www.wikihow.com/Make-Your-Own-Ringtone#Using_iTunes_sub
That link jumps to the method I used. They give you four methods you can use, but I used the third, which is doing it manually using iTunes, to avoid viruses and to get the best sound quality possible.
I have to say, I'm quite proud of myself for making all these ringtones.