I wrote singin' and Duo said: you have a typo ;)
Because you had a typo, hahaha. I know it's very common to write it that way, but just in informal situations with some friends or something similar. it's like "this is 4 u", everyone will understand it, but it's not grammatically right, I think :P
Of course you are right, I was just kidding about the song's title.
This makes me Gene Kelly.
Ah, Alex DeLarge.
Great, now I've got the song stuck in my head!
You're lucky. I had "My Friend Foot Foot" stuck in my head for two days.